You can generally determine your size by measuring the width of your knuckles across the inside of your palm. Then double this figure. The following is a broad generalization of glove sizes but keep in mind that they vary a bit between different manufacturers. The use of hand wraps is recommended. Please keep in mind to wrap the hand and then take another measurement.
Small gloves are 7" to 7.5" medium are 7.5" to 8" large are 8" to 8.5" XL are 8.5" to 9" XXL 9" and up