Labelled weight of wet cat food

[doyenminus]

I weigh the serve of (processed) wet cat food when feeding our cat.

Within the limits of accuracy of the digital scales I use, I rarely find that the package contents reaches the stated weight on the product label.

Has anyone else encountered this, and is the manufacturer short-changing me?

What is an acceptable margin of error?

[phb]

@doyenminus

Within the limits of accuracy of the digital scales I use, I rarely find that the package contents reaches the stated weight on the product label.

Just a couple of questions…

• what type of scales do you have and how old are they? Have you tested them to see if they are still in calibration? If your scales are old and not in calibration, one can use the scales in the fruit and vege part of a supermarket to measure weights are these are likely to be more accurate than domestic type scales.
• how do you measure the net weight? The best way to do it is to weigh the contents and container, then remove the contents and thoroughly clean the container to remove all residues, dry and then weigh the container. The net weight of the contents will be the first weight less the second measured weight. If you measure the contents scraped from the container, then there will always be resides within the container will be make the mass of contents less than what they should be.

@doyenminus

What is an acceptable margin of error?

For the product and do avoid duplication, this has been discussed in this other thread.

Weights on Packaging

Thanks so much for adding that. ASIC has an entry for a ‘Twinview Berries’ being registered as a business name in 2018, but without any detail. They appear to supply more groceries than just Coles as ascertained from ad hits from Google. There is no web presence (a Twin View Berries facebook page is a US raspberry farm). ‘Driving’ Old Gympie Road on Google Maps shows what appear to be multiple berry farms along the road but there are no discernible signs or street numbering, so overall it app…

[doyenminus]

For the purposes of testing, I have two digital scales. One measures to 0.1g and the other measures to 1g. I place one scale on top of the other and TARE them both. I then take a washed empty container including the lid and place that on the top scales then TARE the scales again. Then I place a full container on the scales and take the reading from both scales. I think this is a fair way to get a measurement.

[syncretic]

@doyenminus

I have two digital scales.

Why?

[doyenminus]

Our kitchen has two sections so we have a set of scales in each section. It was in response to the question about the calibration of a weighing device. I only use the two together to check the accuracy from time to time. One scale has greater sensitivity to weigh in 0.1 g increments but has a maximum mass measurement of 2 kg. The other scale measures up to 5 kg but only has 1 g increments. By placing one scale on top of the other and zeroing out both, I can simultaneously weigh an object and compare the readings (which should be the same).

[syncretic]

@doyenminus

compare the readings (which should be the same).

So are they the same all the time?

Have you ever calibrated the pair against a known standard weight?

[doyenminus]

That’s a good question. I only have some old imperial weights, which I maybe should take to a supermarket measure against their scales. They are labelled 2 oz (56.7 g), 4 oz (113.4 g), 8 oz (226.8 g), 16 oz (453.6 g) and 32 oz (907.2 g).

Here are the results

[doyenminus]

Using the same weights on the more sensitive scales

Will report further after testing at a supermarket.

[syncretic]

@doyenminus

Will report further after testing at a supermarket.

Your results are very good I wouldn’t bother. Your old steel weights might be better than the supermarket scales!

Getting back to your original question, weights and measures standards for consumer goods all have acceptable ranges of accuracy. Have you looked this up and does your cat food fall outside?