DavecUK The 100g is what they will weigh, you can put a 300g cup on them, tare them out and the will weigh up to 100g more.
Are you sure? This is not the case with the other 4 scales I have. In fact, it won’t make any sense if that was the case, because then they might as well say 400g capacity as the display can accommodate that.
Maybe you have a version that has a higher capacity?