For size, measure around the largest part of your hand at the base of your thumb with your hand slightly cupped as if you were putting on your bangle. See photo
 
x small       7"      
small          7.5"   
medium     8"     
large           8.5"  add $5
x large        9"      add $5
xx large      9.5"  add $8
xxx large    10"   add $10
 
$7 for Added Heart Charm