I bought a scale a while ago (tip: when I was searching, as well as ‘electronic scales’ and ‘digital scales’, I found what I was looking for with ‘jeweller’s scales’) to weigh my wool. I asked the seller several times how the ‘auto calibrate’ feature worked and got unsatisfactory replies, but the description stated that calibrating weights were unnecessary (like when you buy a lump of metal that’s exactly 50g, 200g, etc.).
When I got it, I wanted to check how accurate it was, but those weights are expensive. I went online to look up the exact weights of 5, 10, 20, and 50 cent, and $1 and $2 coins, and weighed some of my own. perfect!
Remember this won’t work for actually calibrating your scale - like when you put on a 200g weight and tell the scale that this is a 200g - unless you can enter specific amounts, like tell the scale ‘this weight is 3.3g’. But I was very happy to know how accurate it was. HTH
By the way, how many of you have a scale? I wonder whether it’s mostly useful for sock knitters?