Here Welder this is not guite what your looking for but should help. This is the site where I found this http://www.brettunsvillage.com/leather/conversions.html .
As a general rule, each ounce of thickness is roughly equal to 1/64 of an inch in thickness.
As an example, 8 oz leather is 8/64" thick, which is the same as 1/8".
Some simple examples of thickness based on US coins:
A dime = 3 oz
A penny = 3.5 oz
A quarter = 4 oz
A nickel = 4.25 oz So, dig this: 6 oz leather is like two dimes stacked one atop the other.
8 oz is two quarters stacked together.
12 oz is three quarters stacked together.
i know this is not what size to use on what but shere helps you thinks of how thick the leather is.
Russ
ps all so look around the site thay nice pirce on some punces if you need them