Your string could be any length that you want. For the sake of explanation, let’s call that length a “brutita” (after your userid!). Using that string, you can measure things as 2 brutitas (or two string lengths) or 16 brutitas (16 string lengths). If you wanted to get metric, remember the common prefixes milli, centi, and kilo. So a thousandth of a brutita would become a millibrutita, a hundredth would become a centibrutita, and a thousand brutitas would become a kilobrutita. You can use all of the prefixes if you want (deci, deca, etc.), but in normal usage, those three are the most common.