The Conventional Wisdom
Unless your hands are unusually big or small, you can get away with playing standard-size grips. You can also use a static fitting chart like the one below to match grip size to your hand size.
Our New Theory
Finding the correct grip size has little to do with the size of your hands, or even personal preference. It has everything to do with the dynamics of your swing.
How We Tested It
Twenty-four golfers (ranging in handicap from +1 to 7) hit their own 5-iron and five identical 5-irons (Titleist AP2s with Dynamic Gold S shafts), each with a different-sized Golf Pride grip (undersized, standard, slightly larger standard, midsized and jumbo). All markings were covered to prevent any previous size bias. While blindfolded, each golfer was asked to choose the grip they preferred simply by holding each club in their hands. They were then measured for grip size using a fitting chart.
After sufficiently warming up with their own 5-iron, each golfer hit two practice shots out to a target on the range, then hit 10 additional shots that were measured on a Trackman launch monitor. This was repeated for each club (assigned in random order), concluding with their own 5-iron, which served as a control club.
THE SHOCKING RESULTS!
After tallying the results of the pre-hit tests and the data collected by the launch monitor, we know three things for certain:
1. Hand Measurements Don't Work
•16 of the 24 blindfolded golfers (67%) preferred a grip size that was different than their measured grip size in the pre-test.
•After hitting shots, 22 of the 24 players (92%) preferred a grip size that was different than their measured grip size.
•CONCLUSION: Determining grip size through standard static fitting procedures isn't a very good predictor of the grip size that golfers prefer.
2. Neither Does Relying on Your Feel Sense
•21 of the 24 golfers (88%) had standard-sized grips on their own 5-irons, yet less than half of these players (10 of 21) were measured for standard-sized grips.
•Only slightly more than half (11 of 21) preferred the standard-size grips on their 5-iron after hitting test shots with the other 5 test clubs.
•CONCLUSION: If you're playing off-the-rack clubs with standard-sized grips, there's only a 50% chance that these grips match what you'd be measured for in a static fitting, or what you'd actually prefer.
3. You're Playing the Wrong Grips!
•Only 5 of 24 golfers (21%) hit their best shots with the grip size that matched their measured grip size in terms of left/right accuracy. These weren't always the grip size the golfers preferred, either.
•Only 3 of these golfers (13% total) hit the best shots with the grip size that matched their measured grip size in terms of distance control.
•Only 1 golfer (4%) hit the ball straighter and with greater distance control with the grip size that matched their measured grip size.
•CONCLUSION: Your grips are costing you at least 5 strokes per round.
How to Use These Findings
The only way to know what size grips to use is to experiment with as many different sizes as possible. When you decide to make the change, ask the professional who's fitting you the following questions. The answers will go a long way toward making sure the job gets done right.
1. What size grips are currently on my set?
Part of a good trial is comparing your performance with new grips against what you brought to the fitting.
2. Can I hit the same club outfitted with different-size grips?
That's how we performed the test, and it's the only way to accurately test your performance with each size. Make sure swingweights are consistent larger grips will tend to make the clubhead feel too light.
3. Can I measure my swings with each grip on a launch monitor?
It's hard to gauge your results if you're hitting into a net, so make sure the shop has a launch monitor or other shot-tracking device. It's important to base your decision solely on shot data.
Money Well Spent
A set of 14 new grips will run you anywhere from $50 to $100, plus $25 in labor. That's a small price to pay for increased performance without making a single swing change.