Sizing does not have to be hard, it can be very easy. Use this chart to translate your standard size.
Brannock device - if you get sized via a brannock device, make sure you are in a relaxed sitting position. Now, we suggest you subtract a half size from the length, and add +3 in the width. This will be your size in the JK's.
Rule: Length -1 Width +3
For example: if your measure to be a 9.5D, in JK you will be a 9/3E
Brannock length is 9.5 you will be a 9
Brannock width is D you will be 3E