Years ago I built the same kind of app for Windows Phone 8. I can't find any reference online anymore, though I still have the git repo.
It was motivated by my girlfriend stating that it's hard to understand one's size in the various systems that are in parallel use, at least in parts of Europe. Worst part is that some systems have weird overlaps where not only they use the same "alphabet", but also the homonymous sizes partially cover the same range, but don't match exactly. Therefore it's impossible to exactly convert between sizes, and they should be derived from raw measurements.
It was motivated by my girlfriend stating that it's hard to understand one's size in the various systems that are in parallel use, at least in parts of Europe. Worst part is that some systems have weird overlaps where not only they use the same "alphabet", but also the homonymous sizes partially cover the same range, but don't match exactly. Therefore it's impossible to exactly convert between sizes, and they should be derived from raw measurements.