Across the whole of the cycling world everybody is obsessed with weight, it is pretty rediculous really that people stress about grams and spend a disproportionate of money trying to save it on the things.
There is even a certain group of people who have it so bad they have a special name: weight weenies, it is not a slur on their character really as these people tend to have their head screwed on. Whilst they definately have a problem at least they go about it scientifically, they calculate the cost per gram saved then go for the cheapest gains first.
Weight Weenies also acknowledge that the first thing you should look is yourself and the stuff you carry - shaving 1kg from your bike is probably going to cost you £1,000; loosing 1kg from your belly will probably save you £100 in beer!
I'm not a weight weenie but if I need to replace a part on my bike I do take it into consideration, the other half used to rip me for it. She's getting over it now since I keep pointing to her that she is a scientist and her whole profession is based around measurement.
There has always been some talk in the various circles about using an accurate calibrated scale but I' not dropping £30 on a fancy Park Tools number when I can get a funky colour cheap one from Argos. From my testing this thing is spot on - check out how I know below.
Anyways getting to the point of the blog post - how to test its calibration - easy just use coins. The Royal Mint website lists their weight, simply zero your scales and bung on some coins, if they weigh what they are supposed to you are good to go! If you want to get super technical weigh your item then get enough coins so that you have approx the same weight then check the calibration for that amount, simples.
Heres a list of coin weights per the Royal Mint:
Top tip for accurate weighing
The geeks amoung you will note that my scales are over-reading in the picture by 1g this is because the surface of the desk I was using to take the photo isn't even - it has a very slight bow in it. This can have a dramatic effect on accuracy - you should always choose the most level and flattest surface you can and make sure to clean it and the feet of your scales.
You should also note that you can get different readings depending on where on the scales you place the object so you should always try to use the centre of the pad.