Work Safety Gloves in bulk quantities for the larger user or shop buyer
Use a tape measure to find your palm circumerence using inches. That is across the palm from the inside of the base of the thumb eg 8 inches would equate to a medium.
S = 7-8 inches
M = 8-9 inches
L = 9-10 inches
XL = 10-11 inches
XXL = 11-12 inches
If you are in between choose low eg 7.5inches choose 7 (small)