Cadet is a shape, not a size
Golf gloves ask a question no other glove asks. Alongside small, medium, large and so on, there is a parallel range called cadet, and the name misleads almost everyone who meets it. Cadet does not mean junior, and it does not mean smaller. A cadet large is exactly as large as a regular large. It is cut differently: about a quarter of an inch wider across the palm and a quarter of an inch shorter in the fingers.
That exists because hands are not scaled copies of each other. Some are long and narrow, some are broad and short, and a glove tight enough to play in has no slack to absorb the difference. If your fingers are short for the width of your palm, a regular glove either bunches at the fingertips or squeezes across the knuckles, and neither is fixable by changing size. Cadet is the fix.
The formula
expected length = circumference − 0.5 in
cadet = your length is at least 0.25 in under that
Men's bands run 7 to 7.5 inches for small, 7.5 to 8 medium, 8 to 8.5 medium large, 8.5 to 9 large, 9 to 9.5 XL and 9.5 to 10 XXL. Women's run 6 to 6.5 small, 6.5 to 7 medium, 7 to 7.5 large and 7.5 to 8 XL. For a normally proportioned hand, length measures about half an inch less than circumference. Cadet is a proportion test against that expectation rather than a size test, which is why a hand can be cadet at any size, including the smallest one.
Worked example
Your golf glove size is not your glove size
This one catches people who have already looked up their glove size somewhere else. A golf glove is cut to fit like a second skin, because any slack between hand and grip is slip. A winter glove or a work glove is cut with room in it, because the job is warmth or protection and a little space helps. Same hand, same measurement, different answers.
In practice the gap is about one size. A hand measuring 8.5 inches around the knuckles comes out a medium on the standard glove charts our glove size calculator uses, and a large in golf. Neither page is wrong. They describe two garments that happen to share a name, which is a recurring theme in this corner of the site: a boxing glove is sized by the weight of its padding and a baseball glove by the length of the glove itself, and none of those numbers mean anything to each other.
Which hand, and how tight
The glove goes on your non-dominant hand: left for a right handed golfer, right for a left handed one. That is the hand at the top of the grip, and it does most of the holding while the lower hand does more of the steering, which is why one glove has always been the convention rather than two. Nothing in the rules stops you wearing two, and plenty of golfers do in cold or wet weather, where grip is the entire problem.
On fit, err tighter than feels natural. There should be no loose material across your palm, no space beyond your fingertips, and the closure should fasten comfortably rather than straining to reach. New leather feels slightly restrictive and that is correct, because it will stretch. A glove that fits beautifully on the first tee of the first round is usually a glove that will be sloppy in a month, and a sloppy glove twists on the grip at exactly the moment you would rather it did not.
When to replace it
Sooner than you think. A golf glove is a consumable rather than a piece of equipment, and it stops doing its job long before it looks finished. The failure is stretch, not wear: the leather relaxes across the palm and around the heel of the hand, the fit goes from snug to merely present, and the glove starts moving independently of the hand inside it. You will usually feel that as a grip that needs regripping, or as a swing that has developed a hold problem, well before you notice the glove.
The cheap test is the closure. If the fastening is now noticeably further across than it was when the glove was new, the leather has stretched and the glove is past its useful life. And if you have just fitted new grips, do it wearing the glove you actually play in, since grip size and glove condition interact more than either page will tell you on its own. Our golf grip size calculator handles that side of it.