A USGA Handicap Index is a numeral, to one decimal place, that represents a golfer's potential for scoring. A handicap index of 14.5, for example, indicates that a golfer will, on his or her best days, shoot somewhere around 14 or 15 strokes over par.
Handicap Index is not an average of a golfer's scores, but rather an estimate of what the golfer might shoot on his or her best days.
Handicap Index is figured through a complicated formula that, thankfully, individual golfers are unlikely to ever use themselves. Golfers who carry a USGA Handicap Index usually do so through their local golf clubs, and those clubs keep track of the numbers.
For a lengthier definition of Handicap Index and how handicaps are used, read this overview of the USGA Handicap System or check out our Handicap FAQ.
Handicap Index is used to figure course handicap, which tells golfers how many strokes they can take, and on which holes, during a round.
Also Known As: Handicap, without the "index," although this is technically incorrect.
The Golf Guide has a handicap index of 8.6. (He wishes!)