There are some, maybe on this forum or the other place that would violently disagree with you. 'You are not allowed to overfill! it is illegal and trading standards have said so!' these zealots say overfilling is illegal as you are driving other 'legitimate suppliers' that do weigh correctly and do not overfill out of business.he also said net weight was the minimum and no body would prosecute with any that are over weight.
So self checking with certified check weights traceable to national standards isn't allowed then...Advice from Trading Standards:
It doesn't say you have to buy a TS approved weighing machine, however it must be 'passed as fit for use for trade' by an inspector of weights and measures (trading standards officer).
So I read this to mean we need an accurate balance and to be legal for use in trade it must be stamped (and presumably checked) by a trading standards officer.