Hoods and Leather Conversion

Well I'm in the middle of making a new hood, i also need to buy some more leather. One of the issues i have with all the leather suppliers is they measure there leather in different thickness. It took a while but i finally found out what the difference was and found a conversion chart

Leather Conversion Chart

Inch	Ounces	Irons	Millimeters
1/64	1	0.75	0.4
1/32	2	1.5	0.8
3/64	3	2.25	1.2
1/16	4	3.0	1.6
5/64	5	3.75	2.0
3/32	6	4.5	2.4
7/64	7	5.25	2.8
1/8	8	6.0	3.2
9/64	9	6.75	3.6
5/32	10	7.5	4.0
11/64	11	8.25	4.4
3/16	12	9.0	4.8
13/64	13	9.75	5.2
7/32	14	10.5	5.6
15/64	15	11.25	6.0
1/4	16	12.0	6.4
17/64	17	12.75	6.8
9/32	18	13.5	7.2

The modern apprentice has a link for Slijpers Hood software.
Slijper's Cannon Indian hood pattern software - shareware