X and Y are the two measurements we use for underarm crutch sizing. X is the distance between the top of the pad and the top of the hand grip. Y is the distance between the top of the grip and the bottom of the crutch tube or tip.
Using a tape measure, measure down the middle of the crutch from the top of the underarm pad to the top of the hand grip.
Using a tape measure, hook the end to the bottom of the crutch tip or tube and measure to the top surface of the hand grip. Specify if Y was measured with or without a crutch tip. We will make sure the length is correct when we know what kind of tip you'll be using.
Do you often stub your crutch tips on the ground? It may mean your crutches are too long. Do you feel stoop shouldered? They may be too short. Try this test: Standing tall with your crutches at you side, allow your hand to drape over the grip. The deep crease between the palm of your hand and your wrist should line up with the top surface of your grip. If that crease falls above the top of the grip, there is a good chance your crutches are too short. If the crease is below the top of the grip, your crutches are probably too long.