Understanding average weights…

Average weights is a complicated subject and perhaps this is why many sites procedures do not comply with the legislation. In this post I’ll break down the rules, so that you can check your systems to make sure your procedures and records comply.

average weights

Minimum weight or average weight?

If at all possible I would always advise sites to run their weight systems by minimum weight rather than average weight, as it makes things so much simpler!  However, to run to minimum weight you need to check your packaging first (or specification if you produce product for further processing). If your pack (or spec) has the e mark, then this indicates average weights, so you would have follow the average weight rules that I’ll go through below.

If there is no e mark then you can run to minimum weight, which means that you need to carry out weight checks, but the frequency and sample rate is up to you – as long as the pack weight is at least the minimum weight, that’s all you need to prove.

What does it mean to run average weight?

Where your product has an e mark, it is a legal requirement that you meet the average weight rules and be able to prove (through records) that you have done so. The average weight rules are split into what they call the ‘3 packers rules’.  If trading standards were to visit you, they would want to see evidence of your compliance all 3 packers rules.  Generally, when I visit sites they usually meet the average weight rule, but forget to comply with the other two rules.

The 3 packers rules are:
  1. The average of the batch must be at least the nominal weight
  2. There must be no more than 2.5% T1s
  3. There must be no T2s in the batch

It sounds complicated and it is a little, but we can break it down to try and explain it.  Before we explain the 3 packers rules, there are 2 really important points to understand first:

  • You must define what you mean by a ‘batch’
  • You have to work out what sample size to apply

It’s important that we understand what ‘a batch’ is, as there are a few rules around what can be defined as a batch.

A batch must be:

  • The same product (recipe and weight)
  • Made on the same day
  • Made in the same place (line)
  • From one production run
  • Be no more than 10,000 units
  • When checks are carried out at the end of the line, the maximum number for a batch is the hourly throughput

Once we’ve established our batch, we must work out how many samples are required to be assessed per batch.

The legislation states that the sampling rate must be at least 50 packs per 10,000 packs produced, the minimum time to produce 10,000 packs is 1 hour and the maximum allowed is 1 day. Here’s a guide:

  • If you make less than 10,000 units per day, then you must sample 50 units across your run.
  • If you make more than 10,000 units per day, you need sample 50 packs from each 10,000 units made.
  • So if your throughput was 10,000 units per hour you would need to sample 50 packs per hour.
  • If your throughput is 30,000 units per hour, then you’d need to sample 50 packs every 20 minutes (1 hour divided by 3).

3 Packers Rules:

Now you know what your batch is and how many samples you need to check in that batch per hour, then you need to confirm for each batch that you’ve met the 3 packers rules. I’ll go through each one individually.


For all the samples that you’ve taken you need to confirm that the average weight is the same or greater than the weight declared on pack (known as the nominal weight). So; add up all the weights of the samples taken and divide the total weight by the number of samples, this will give you the average weight for the samples taken.

RULE 2 – The batch must not have more than 2.4% -T1’s

So, now we need to understand what is meant by ‘-T1’.  The legislation defines ‘T’ as the tolerable negative error, but just try to think of it as a set quantity that is taken off and added onto the weight declared on pack. First you need to find out what ‘T’ should be for your pack size. The legislation provides this table:

Tolerable negative error

Nominal quantity in grams and millilitres

As a % of nominal quantity

g or ml

5 to 50


from 50 to 100


from 100 to 200


from 200 to 300


from 300 to 500


from 500 to 1,000


from 1,000 to 10,000


from 10,000 to 15,000


above 15,000


In order to work out what ‘T’ would be for your pack, you would need to look up your pack size in the left hand column and then look across to see whether a % or g/ml is provided.

WORKED EXAMPLE 1: – Your pack size: 75g

Let’s go with the g or ml column first as that’s easier.  If your pack size was 75g for example, it would sit between 50 and 100g, reading across the columns on the table above – you’ll see the tolerable negative error for that pack size is 4.5g.

So T = 4.5g.  So, T1 (which is T x 1) is 4.5g x 1 = 4.5g.

Therefore to work out –T1 would be 75g (for your pack weight) – T1; 75g – 4.5g = 70.5g.

So for this example, to comply with rule 2, that no more than 2.5% of your samples must be –T1, means that – no more than 2.5% of your sample must weigh less than 70.5g.

So to do this, you would need to work out what –T1 is for your pack size and then, highlight how many of your samples weighed from your batch weigh less than your –T1 figure.  Then work out what % this is per batch.

WORKED EXAMPLE 2: – Your pack size: 450g

Going back to the table above, you’ll see that if your pack size is between 300 and 500g and read across the table, you’ll see that you’re not provided with a g/ml number but a %.  For a pack of 300 – 500g it’s 3%.  This means you need to work out what your T is by working out what 3% of your pack size is.  So for a pack of 450g it’s 13.5g, so T would be 13.5g.  –T1 would be 450g – 13.5g = 436.5g.

RULE 3 – None of the packs must be -T2

So, we’ve worked out what the –T1 is above, now we need to work out what T2 is.  Easy – it’s just your T figure x 2.

So, -T2 is your T2 figure taken away from your declared weight on pack.

To comply with this rule, you must make sure that none of your packs weigh –T2 or less.  Any of your samples that you weigh that are –T2 must be disposed of, or re-worked.  If you get –T2’s in your batch you should also apply corrective action to make sure you increase your sampling, in case there are other –T2’s in your batch.  In the worst case, you would need to check all of the packs produced to ensure that you don’t send out any –T2 packs, as Trading Standards would see these as ‘illegal’ packs.

Signing off the batch

For each batch produced you must positively confirm that you’ve adhered to the 3 packers rules. This means you need to work out the average weight of the batch and record it. Then sign it off to say it conforms (if it does).

  • Calculate the % of -T1’s in the batch and again sign if off to say it conforms if it’s less than 2.5%.
  • Confirm that there have been no -T2’s for the batch and sign it off.

Where any of the batches do not pass these rules, corrective action must be applied.  The aim of the corrective action must be to ensure that the batch is adjusted to make sure that it meets the 3 packers rules before it is dispatched.  You would need to ensure that all the –T2’s are removed, that there are no more than 2.5% -T1’s and that the average weight of the batch is at least that on pack.  To do this, you can go through more samples (depending on the scale of the problem) and record the results, or go through all the packs and record the results.

Working with volume rather than weight

If you declare your product in volume rather than weight (ml or litres), you will probably check the weight (and apply the 3 packers rules) in weight.  It is important if you do this that you know the density of your product, as you’ll need to convert your weight to volume to be able to determine if the weight is correct.

Next steps

If you’re updating your quantity control systems, for average weight or minimum weights, you need our documentation pack – Pack 17: Process Control.

Not only does it include quantity control, process control and traceability.

It’s everything you need to improve process control on your site.

Have your say…

103 thoughts on “Understanding average weights

  1. Hi Kassy,
    say your units “per run” is only 1000 – do you sample proportionately or do you still have to do 50? Also, what if you have a multi-head filler – does this factor into it? We have a range of fillers from 1 filling head to 48 filling heads?

    1. Hi Alex,
      I’m afraid you’d still need to do 50. If you have 48 filling heads, in theory you should be able to show that you’ve sampled them all – because each head could be filling differently. Perhaps one rotation of the filler – gives you 48 samples per run. Producing just a 1000 samples on a 48 head filler must have it’s problems, so I can appreciate this probably isn’t the answer you’d like 🙂

  2. Hello Kassy when you say ” unit” do mean retail unit as in a can of beans, a package of bacon or a bottle of pop? . My application is bread , frozen dough to be exact and I am running a slow line packing 60 pieces into each case. Probably doing about 100 cases per hour. My strategy was to take a case (60 pieces) at start , middle and end of run and do a verification check prior to shipping. This means N=180.
    My nominal or declare weight is 90 grams, what do you think?

    1. Hi Clem,
      A unit for average weight, is the unit where the weight is listed. For example, a retail pack would have the nominal weight listed on the pack, so one unit is one product. If you are supplying a box of frozen dough, where is the nominal weight listed? Is it on the box or on the specification for the individual frozen doughs. It’s the nominal weight that you have to be able to prove. Are you sure you are working to average weight on your frozen dough? Typically, product that goes for further processing would not need average weight, and so, you’d work to minimum weight.
      The number of samples you need to take depends on how big the production run is. 60 pieces would be a minimum for a run under 10,000 units. How long would it take you to produce 10,000 units? This will obviously depend on whether a unit is a box, or whether there are 60 units in a box…
      Let me know and I’ll try to help further.

  3. Thanks, I am declaring 90 grams but as you correctly suspected it is the retail customer that is taking that case of 60 pieces and repackaging it as they deem appropriate lets say into 3-packs. What I want to do is validate that the process delivers pieces that after final in store bake off will be 90 grams or more as per my specification. It is the Retailer who will have to deal with weights and measures.
    Thanks again

  4. Hi Kassy,

    Is the weight of the packaging taken into consideration when calculating the T1/T2? Or is it solely on the contents of the packaging?
    Thank you in advance for your help

  5. Hi Kassy

    How would you recommend keeping records of compliance to packer rule 2 and 3 when using manual checks? If I weight 10 packs per hour manually, 1 pack between T1 and T2 would straight away give 10% when the limit is 2.5%.

    Best regards

    1. Hi John
      Keeping records of compliance to each of the packers rules is a must, so that you can prove that the product that you have produced in the past was compliant. You would need to prove this to Trading Standards on an inspection. Remember, you 2.5% is across your batch. So, if you weigh 10 packs an hour, yes you are right 1 pack would be 10%, but if you did a run of 4 hours on the same batch, then 1 pack over the 4 hours would be 2.5%.
      Thanks, Kassy

    1. Hi Renata
      If you follow the letter of the law, you shouldn’t ‘give away’ more than 2.5% T1 or any T2’s. But in practice, Trading Standards are not going to worry if you are giving the customer too much. Unless, that is, you are producing a product with a nutritional claim, where the excess product could mean you are not meeting the claim.
      Thanks, Kassy

  6. Hi

    From my previous comment I meant the below list in particular – is this more of a guideline or a recognised definition by governments?


    It’s important that we understand what ‘a batch’ is, as there are a few rules around what can be defined as a batch.

    A batch must be:
    •The same product (recipe and weight)

    etc. etc.

    1. Hi
      Ok, I see. The list is my interpretation of how to define a batch – its not part of the legislation.

  7. Hi Kassy
    Thanks for the above – very good explanation.
    One question I have is:
    We are planning to pack 1.5 litres of product into saleable units and use the minimum weight as packaging does not have the average logo.
    We will weigh every unit and ensure that these are all above our calculated minimum of 1536 ( product and package ) or will be rejected.
    These will then be packed in cases of 6. If we record the weight of 1 individual unit every 15 minutes along with 1 case of 6 is that sufficient
    to meet the requirement – potentially we will produce 5000 individual units every 24 hours.

    1. Hi Keith,
      You’ll be pleased to know – that if you’re not declaring your product as being packed to average weight (by adding the e Mark) then you don’t need to comply to the average weight regs. So you can define your own sampling plan, which means what you are suggesting would be fine.

  8. Hi Kassi

    Is there a need for T1’s to be destroyed? I have procedures from a previous business that states T1s should be destroyed as well as T2. Was the technical team there being overly cautious?

    1. Hi Laura,
      You can’t have more than 2.5% T1’s in the batch. Therefore, if your monitoring shows (during production of the same batch) that 2.5% or more has been achieved, then you could in theory increase the dough weight at the divider and/or increase the batch size (i.e keep producing) to ensure that the perecentage of T1’s is reduced across the whole batch.
      If this isn’t possible, then the right number of T1’s would need to be wasted to ensure that there were no more than 2.5% in the batch.
      Does that make sense?

  9. Hi. I used to run a line making ready meals. On a minimum weight system,the average weight is the number of kilograms produced divided by the number of meals produced and the more meals produced let’s say 5000 meals and you altered the weight slightly then it would take time for the average weight to lower as compared to less meals produced.
    Now on nominal weight program, it doesn’t follow that rule. …Lets say i produced 5000 meals and the number of kgs produced was 2,040,000 then the average weight would be 408 grams and should take a while for it to lower if you altered the weights less but it doesn’t ….the average weight changes every few minutes. ..just wondered why. Hope you get in touch
    Kind regards

    1. Hi Matthew,
      I’d be happy to help, but I’m not sure I understand what you’re asking. Are you saying that if you reduce the weight of the product, the average weight on your system should come down slowly and it doesn’t because it goes up and down every few minutes? If that’s the case, it would either mean that the weights of the product being checked varied massively (a wide enough weight range to change the average weight quickly), the batch size in the machine isn’t set up right or there’s something wrong with it!
      Let me know if I’ve misunderstood 🙂

  10. Hi Kassy,
    Thanks for this information
    We run a spirits bottling line @ 200 bottles per minute both with/ without the e-mark. ( 192,000 bottles a day)
    What quantity of bottles should you check for fill level & how often should you do it?
    Thanks for the help

  11. Hi Kassy,
    We are a small microdistillery. Our production run is an average of around 1344 bottles at 350ml. Production takes around one day as the process is mostly manual. We do not have the ‘e’ mark on our bottles. We have 4 pneumatic filling heads. Currently we do 12 samples in all, 3 each for each filling head at the beginning of each run. Are we currently sampling enough? What would be an ideal sample plan for a production run of this size and what would be the best way to record our sampling?

    Thank you.

    P.S: I have signed up to the news letter and not sure where I can download the calculator mentioned above.

    1. Hi,
      I think Mel’s helped you out with the calculator, so hopefully you’ll have that now. If you do not have the e mark on your bottles, you don’t have to run to average weight and therefore, you can pick the sample size that you think works for you best.

  12. What’s the view on products that change weight after packing. For example, if at point of pack, product batch complies with average weight legislation, but during distribution/ shelf life, net product weight changes, due to for example moisture loss, oil migration etc, and may lead to products on sale that fall outside the legislation. Does this have to be compensated for?. UK Legislation states at point of pack, WELMEC guidance (which TSO’s generally use) ‘recommends’ adherence throughout distribution.

    1. My view would be that the pack should weigh the nominal weight declared on pack, at the point at which the customer buys it. However, legally you would have a defence if challenged, if you could prove that the packs complied with the 3 packers rules…

  13. Hi Kassy,
    Great article really helpful,

    One question when I was looking at the EC Directive the table that works out the ‘tolerable negative error’ is divided into Class A and Class B? I work in a bakery and just wanted to check I’m going by the right category?


  14. Do any other manufacturers create their own T2 test packs to ensure their machinery is working correctly?
    If so, how do you go about this?

    1. Yes and I think your online checkweigher company may provide these too. It doesn’t need to be actual product, it just needs to be the right shape, size and – weight of course! I would recommend you speak to the manufacturer first, as they may have the easiest solution for you.

  15. First off great article – thanks.

    Does anyone do small runs and average weights and is it worth it or even do-able? For the area we can change to average weights, some batches are <50 units, most are 50-300 and the biggest 500. We packs lots of different 100g packs of produce currently to minimum weights. We use the Marco weighing system for context.

    1. Hi, if you’re doing minimum weight and you can stick to that, I would highly recommend doing that. I’d only do average weight really if you have to – either for your customers or if you’re exporting product. Thanks, Kassy

  16. HI Kassy, I’ve done a bit of extra research since my original post. For batches <100 you have to have a sampling rate of 100% so this makes it not worth it.
    For actual calculations and sticking to the statistics etc the Marco (and I assume similar systems) do all of this for you and along with the sampling scales make compliance easy. It was just the cost/benefit of small runs vs savings in using the average weight rather than minimum that I was querying.

  17. Dear all,
    can you help out with a industrial product in Bigbags 500 and 600 kg? What is the tolerance here? Some customers have really low tolerance and we are asking ourselves how to deal with weight claims.

    1. Hi Kate
      If they are industrial bags, they won’t need an e mark and therefore you don’t have to comply with average weights. 🙂

  18. Hello, if I have a batch of 10000 units to pass through the checkweighing machine and I have a T1% of 2.5% (25 units) but I am reworking around 1000 units with damaged packaging etc while in run, the total amount of accept packs would show 11000 units at the end of the run. Would this mean that I could potentially have too many T1% than legally allowed? Hope that makes sense. Thanks.

    1. Hi John
      It does make sense yes. Couple of thoughts – if you’re reworking them because they have damaged packaging, shouldn’t they have already been check weighed and therefore, in theory – they should be of the correct weight? Or are you saying the damage to the packaging changes the weight. If that’s the case, I would rework these under a derorgation, so that you can explain the corrective action.
      I hope that helps.

      1. Yes the units have already passed through the checkweigher but they need to be repackaged in the same area as the checkweigher and resent back through the machine for metal detection (and checkweighing) also once they have been opened. These rework units are reworked instantly (within 5 minutes or so) throughout the run until all units have been completed.

        The order of machines are:
        Packaging – checkweigh/metal detector – labeling.

        The problem I would have control is if damage to packaging is after the checkweigh/metal detector.

        1. Hi John
          Ok, so I would run this under a concession (derogation). Because they have already gone through the check weigher they have in theory, already been verified. Therefore, any T1s that you get should come from the product that has just been weighed for the first time.
          Does that make sense?

  19. Hi Kassy.

    Just to say firstly I really find the Techni-k to be an excellent resources for those working in the food industry. I just have one query related to T1 checks; we have been asked by a customer how we perform our daily checks for T1 using test packs. Now I am sure it is very simple and straight forward but just wanted to make sure that I am not missing something important.

    Any help would be appreciated.

    Thanks 🙂

    1. Hi Siobhan
      That’s great to hear! Can I please ask first – do you have inline check weighers?

  20. Hi there,

    I would like to know if we get a product that has a weight somewhere between T1 and T2, how is it classified?

    E.g. T1 216g and T2 is 207g, and the product weight is 214g?

    Thanks for your help!


    1. Hi Stacy
      The rules do not apply to packs of 5g or less. This means that you don’t have to comply with the 3 packers rules. You still have to target a 5g weight, and you can still apply the same rules generally, but you don’t have to comply with T1 and T2.

  21. Hi Kassy,
    Thanks a lot for your article.
    There is one detail I still do not understand. What to do with product which is between T1 and T2.
    You have presented example of product weighing 450g T1 is 436.5g and T2 is 423g. You can’t have any below T2 and less than 2.5% of T1 – so far clear.
    But what you should do with product which is e.g. 430grams aka between T1 and T2?
    Many thanks

    1. Hi Milan
      Any product that is between T1 and T2 weights are classed as T1, so you treat them as a T1.
      I hope that helps.

    1. Hi Chloe
      You would calibrate and verify the accuracy of the weighing scales. The verification of the T1 and T2 is someone sense checking the results and signing them off.

      1. Hi Kassy,
        Thanks for coming back soo quickly.
        We have in line checkweighers that are calibrated annually and we verify the accuracy of our scales. However, our customer would like us to verify our T1-T2, (it is not enough to sign off the print out).

        Do you have any suggestions as to how we would do this?

  22. Hi kassy,
    Thanks a lot for making this to easy to understand.
    Although I have a question regarding the legal requirement of following minimum weight or actual weight. Is there any categorisation to follow these.

  23. OK,
    For example I am working in bakery plant (ready to eat product), so is there any legal requirement that I have to follow what type( minimum or average) of weighing system.

    Hope you get my point.

    1. In the UK bakery products of more than 300 or 400g have to be average weight. If you have an e mark on the product then it must be average weight. If you’re selling the product in the EU it must have an e mark and therefore average weight. Other than that, it’s up to you.

  24. Hi Kassy,

    My question mostly surrounds understanding what a batch is. I work in the malting sector. We have a packing line for 25kg sacks. We are looking at putting an inline checkweigh in to reduce give away by going from min to ave. Our products are mostly the same, barley that has been steeped, germinated and then either kilned or roasted. The end process is where the product changes character. Roasting or kilning at different temps imparts different colour and taste characteristics. If we are running all day on the same pack sizes but changing between these different types of malt, say doing 10 t of one then 30 t of another, are these all seperate batches or all one batch. We also mill some of our product so we may run say 20t of a product and do 10t whole and 10t milled; again would these be two separate batches or all the same batch. We do not produce more than 10000 packs in one day all is produced on one line in succession. We also produce products such as wheat and oats…. I imagine that these would be separate batches.

    1. Hi Ian

      It’s up to you what you deem to be a batch. But, it does need to be by pack size as a minimum.

      Personally, I would separate them by physical form too – so milled or whole.

      The quantity in the batch depends on the number of packs, not the total volume… So, no more than 10,000 packs.


      1. Sorry that this is a little belated… But thanks for the reply.

        I had forgotten that i had posted this as the project got postponed.

        I have another regarding the checkweigh.

        Is it necessary to create T1 and T2 test pieces, such as pre weighed bags, and run them through the machine each day?

        I suppose my questions are, does it need to be done? What should the frequency be? Is it necessary to use a pre weighed / underweight sample bag of our product or could i use some actual weights?
        Do you have any advice for such a large pack size (25kg)?

  25. Hi and thanks for this interesting article.
    A quick question, we are working with small meat producers in the UK, preparing cuts of meat rather than processed food.
    Do these products have to be average weight, minimum weight or is this outside the regulation given the small ‘batches’ – there are only so many steaks you can produce from one cow!.
    Also, post Brexit, is the ‘e’ symbol still compulsory for selling at average weights (e.g. mince, where the notion of batch is more relevant) – how do you prove that you were working at average weights or minimum weight?
    Many thanks!

    1. Hi Patrick
      I would imagine that you’re labelling the product with the actual weight rather than average weight? In which case you wouldn’t have the e mark on the pack and average weights wouldn’t apply?

  26. Hello there,

    Could you explain where do we conduct -T1 test to verify that a checkweigher is working correctly? Also is it a legal requirement to conduct -T1 test?

    Mostly -T2 is used in food manufacturing as a requirement to check that checkweigher are working accurately.

    Many thanks,

    1. Hi Shahzada
      I’m not sure I’m following your question exactly. You have to carry out checks of your scales to prove they’re accurate. But you wouldn’t necessarily do this with -T1 or -T2 weights, unless you have an inline checkweigher. The key is to check that the scale is accurate for the range of weights you are putting on it – highest to lowest.

    2. Hi Shahzada,

      I had exactly the same question and I’ve got an answer. It is only required by M&S to conduct T1 test to verify checkweigher. So if you do not supply to M&S – you are perfectly fine to test checkweigher only against T2

      Hope it helps

  27. Hi Kassy,

    Like the others above, this is a great article and very concisely written in plain English, and easy to follow. However, I have a query about multi-packs or packs containing multiple parts (each is packed individually) then collated in a carton (sales unit). e.g. a sales unit has 4 parts each of which is weighed at packing to average of 100g e. There is no weight control on the sales unit. Is it right to declare this as 400g (4 x 100g e )? Or should we be considering something different?

  28. Hi Kassy,

    Can you clarify this please. How should a business weight code a pack that isn’t checkweighed, but the pre-packed components are?
    e.g. 4 packs each of 100g are produced using the average weight system. These are packed into a sales unit (carton). Is it right to declare as 400g (4 x 100 g e)?

    1. Hi
      It’s typical to say 400g e – but you could also put (4 x 100g) as well. The key is not to be misleading, neither of which are.

  29. Hi Kassy,

    That is such an understandable explanation, thank you.
    I’ve got a question.
    Before each of the production run we need to verify the checkweigher (for each product)

    Is it a requirement to use both T1 and T2 test packs to verify the checkweigher?
    If I set up my checkweigher to reject anything below T1 shall I verify it with both T1 and T2 test packs?
    Hope the question makes sense, thank you!

    1. Hi Vika
      If you check that it rejects T1, then you’re essentially checking T2 at the same time. So I’d just do T1.

  30. Hi Kassy,

    Very clear article!

    But still one question 😉
    Can you give a reference to the ‘official’ text where the max of 2.5% T1 comes from?
    I don’t find it in EU law. French customers are referring to their national law, and in there a max of 2% is mentioned.


  31. Hi Kassy,

    Probably this was mentioned somewhere in the comments, but I have a query regarding manual checks and use of checkweighers.
    Do I need to carry a manual weight check if I use a checkweigher that records the batch details and provides print out or information is recorded on a server? Of course this will be still calibrated and reject arm verified etc. Thank you!

    1. Hi Petya
      I’m not sure I totally understand your question. Do you mean – a manual weight check of the scale for accuracy? Or do you mean a manual weight check of the product? The answer to the first would be yes and the answer to the second would be no! I hope that helps whichever question/ answer it is 🙂

      1. Hi Kassy,

        Apologies for the confusion. My question was related to the manual weigh check of the product, so your answer is very helpful.


  32. Hi Kassy,

    Regarding the no more than 2.5% -T1’s, is it pertaining to the batch per hour ( eg. 10000 output ) or to the 50 samples per hour?


  33. Hi,

    If you have an in line flow meter set to only allow product through that have reached the desired target, is it acceptable to use a check weigher to verify the flow meter is accurate at the start of a run or do you still have to abide by the sampling rate you outlined.

    The reason I ask is the units being produced are 45kg and we do not have an in line check weigher so to weigh 50 units would be quite cumbersome.

      1. Hi Kassy,

        Thanks for the reply. From the documentation I can fid for Irish legislation it states weights between 5g and 55kg are deems a package.

        Not sure if this has been updated as the document is from 1981 but would the flow meter check be valid in this case?



    1. Hi Kassy,
      We are producing product e 300g, tare is 20 g, according to above calculation t2=282g, therefore 20g of tare is automatically subtracted by the in line checkweigher. If t2 is solely net weight of product, is testing 280g of a pack(product+tare) a correct weight set to challenge the checkweigher? In other words should t2 test pack weigh 282g+ tare 20g or just 282g(includes tare).
      Thank you

  34. Hi Kassy
    Great article and valuable comments from food industry colleagues. I have a question regarding tolerance in g or percentage when you verify online checkweighers as part of routine/ retailers requirements i.e. start/ middle/ end of each production run etc., where you put nominal weight on a calibrated scale and then check it on checkweighers in dynamic mode/ in operation- what should be the tolerance in +/-g or %age?
    We are ware of zones in indecision and standard deviation to check accuracy of scales during annual calibration. This question is about tolerance during routine verification using nominal weight and how low the T2 test pack should be from the actual T2 weight. Is there any industry best practice around this?

  35. Hi Jawad

    Thanks for your comments, we really appreciate your feedback on the article. For verification the tolerance needs to be based on the accuracy of the machine. I’m asking a specialist in this field if he could reply about the zone of indecision for me.
    Thanks Kassy

      1. Hi Jawad,
        We didn’t apologies – I was on holiday and I thought it would be quicker for them to reply than me. But I’m back now – so.. Regarding the zone of indecision this is the variation in weight that’s caused by the product travelling over the scale. I’m not sure how this relates to your question on T2 packs? The contractor that you use to calibrate your scales should be able to work with you to establish the zone of indecision and how that inaccuracy should be incorporated into the weight checks that you do.
        If I’ve not answered your question, please come back to me.

        1. Can you direct me to any guidance on how much below T2 to set a reject test pack, is it suitable to say 1g below or should it be a percentage of the pack weight? Do we also need to take the ZOI into consideration at this stage?

          1. Hi Pamela
            You need to take the zone of indecision into consideration, but you always do it worst case. So add it onto the T2 ratehr than take it away – so you should go above, not below. Does that make sense?

  36. My business runs product through an inline checkweigher system( loma). The batch report calculates the average weight no of T1s and T2s below 2.5%. Manual checks are every 30 minutes sampling 3 packs per 30 minute. Run time consists of 10 hours, up to 30000 units produced. My questions is do we need to do the weight checks? Are we covered by the automated batch report from the checkweigher.
    Do we need to apply the packers rule 2 and 3 or are we legally covered.
    T1 and T2 set automatically by the machine when entering the nominal. All T1 and T2 are set correctly accordingong to % guidelines.

    1. Hi Stuart
      You still need to apply the rules, but the verification is reviewing the report produced and signing it off. It will still require action if T1s are greater than 2.5% I presume, unless the checkweigher starts rejecting these for you?

  37. Hi Kassy,

    It is such a good explanation.
    I’ve got a question.
    We are going to implement the average weight procedure for our product.
    For using e-mark on our package, is there any concern about registration process in some authority or can add by ourselves by following e-mark specification?

  38. Hi Kassy,

    I’m a bit confused about the defining a batch section. I just don’t understand why a batch size is limited to 10,000 units (around 3 hours production for us). In our setup none of the staff come in contact with the product during packaging, therefor putting a limit on units per batch seems completely arbitrary. For us from a traceability perspective surely the important part is all about the raw materials in the product and that they have been processed correctly/safely?

    All the best,


    1. Hi Jacob, I’m not sure I understand your question. You seem to be relating quantity directly to traceability? The ‘batch’ only refers to the batch for average weights. You don’t have to use the same definition of a batch for everything else too…

  39. Thanks Kassy, So if the ZOI is 1.5g we set the t2 test pack to T2 +1.5g, would that not prevent it being rejected in some cases?

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