Question

Why is a match box not measured in SI system​

Answer 1

Whenever you measure in S.I system you have to maintain the standard form. As match box is smaller than meter it is not measured in S.I system.

Answer 2

match box is not any thing which is used to find the quantity. Or if at all u use it then, ur match box's size may be not that of mine. so this is the reason, it is not same everywhere it is not a uniform measure. so there is no SI system for match box.