Hands comes in of sort of shapes and sizes and varies a lot, but we have made this guide.
Medium fits: Grip 1 with a regular grip + at least 1x overgrip and thicker grips.
Small fits: Grip 0 with just 1x overgrip and thicker grips.
HAND WIDTH (CIRCUMFERENCE)
With your hand open, measure around the circumference of your hand, excluding your thumb, at the base of your knuckles.