The IMAK Arthritis Gloves fit tight for the compression support. If you measure closer to the next size I would size up, just to ensure you don't get a size too small that you cannot get them on. To find out what size to order, measure across your knuckles:
X-Small fits: Up to 2-3/4 inches.
Small fits: Up to 3-1/8 inches.
Medium fits: Up to 3-1/2 inches.
Large fits: Up to 4 inches.
X-Large fits: Up to 4-1/2 inches.