Size measurement is the most critical factor in having a knife that truly fits. I build the knive to the measurements of your hand. If these measurements are not correct the knife will not fit your hand the way I want. 

The width of the hand is taken at the knuckles. Best to have the hand relaxed and measure as shown above. You want the exact width of the relaxed hand. The width is the most critical measurement. 

The length is from the web between the fingers to the end of the longest finger. The concerns of overlength and underlength as described above are important.

Scanning the hand with a ruler to the side has been very successful in obtaing the necessary measurements. Then email the scan to me. A coin or ruler is necessary in the scan to check for any enlargement or reduction in size.