Wrap a tape around your dominant hand at the knuckles, excluding the thumb. Make a loose fist while measuring.
Glove sizes: 6.5–7" = XS, 7–7.5" = S, 7.5–8.5" = M, 8.5–9.5" = L, 9.5–10.5" = XL.
Some brands use numeric sizes that match circumference inches directly: size 7 = 7" hand, size 8 = 8".
Leather gloves stretch with wear. Buy snug — they'll mold to your hand within a week.
Touchscreen gloves should fit closer to maximize finger sensitivity. Snow gloves can be a touch looser for warmth.