How to measure to determine soccer goalkeeper glove size
Measure the circumference of the part of your palm just below the knuckles, excluding the thumb. The measuring tape would be wrapped around your hand below your knuckles, leaving all five fingers free.
Round this number up to the next whole inch.
Add 1 to the measurement to determine your soccer goalie glove size.
ie. 7.5" -> 8" + 1 = 9. Thus, 9 would be the goalie glove size.
Measure both hands, and base the glove size on the larger measurement if they are different.
Goalkeeping gloves should be worn big, generally 1/2" to 1" over the end of your fingertips.