Metric to standard tool conversion

[survivor]

I am trying to figure out what the metric size of a few standard wrenches i own.

5/8=?
11/16=?
13/16=?

A 1/2 an inch i see is a bit smaller than a 13mm, i know i should only use the right tool but these are brand new snap on wrenches i would like to use maybe on a travel bag.