The short answer: firm enough that a putt you miss would roll about 17 inches past the hole. That was Dave Pelz’s answer from his short-game research, and he said it holds whatever the length of the putt. It sits between two ways to miss. A putt that stops short never drops. One that arrives too fast makes the hole play smaller, or lips out: in TrackMan data published by GOLF.com, a putt rolling fast enough to finish a foot and a half past makes the hole play about 25% smaller on a flat green, and one that would finish five feet past makes it play 63% smaller.
This article goes with episode 11 of HYTON Golf, our video series that cuts golf open in 3D. It explains what speed does to a putt, not how to make a stroke. Every fact below is linked to its source at the end.
Key numbers
| Number | What it means | Source |
|---|---|---|
| 108 / 101.6 mm | The hole’s diameter and its minimum depth | International Golf Federation (2026) |
| About 40% | A 1.68-inch (42.67 mm) ball’s width compared with the hole’s (our arithmetic) | R&A Rules of Equipment |
| About 1.6 m/s | The most speed a ball can have and still be captured by the hole, about 3.6 mph | Holmes (1991), via Hogan & Antali (2025) |
| −25% / −63% | How much smaller the hole plays for a putt rolling fast enough to finish 1.5 ft or 5 ft past, on a flat green at about 10 on the Stimpmeter | TrackMan data, GOLF.com (2020) |
| 17 inches | How far past the hole a miss rolls at the speed that holes the most putts, by Pelz’s research | Dave Pelz, GOLF.com (2025) |
| 6 ft / 12 in | Footprints pack in within about 6 feet of the hole; the last 12 inches are almost footprint free | Dave Pelz, GOLF.com (2021) |
| −25% / −4% | How much smaller the hole plays uphill and downhill on a 3° slope, for putts set to stop 0.30 m past | Sheppard, Hurrion & Collinson (2016) |
More numbers from the series, each with its source: Golf by the Numbers.
Watch the episode: How Hard Should You Hit a Putt? on YouTube (6:10).
The hole
Putting is a big share of the game: a 2025 paper by John Hogan and Mate Antali in Royal Society Open Science puts it at 40 to 45% of all golf shots. So start with the target. According to the International Golf Federation, the hole must be 108 mm in diameter, about four and a quarter inches, and at least 101.6 mm deep.
The Rules of Equipment say the ball must be at least 1.680 inches, or 42.67 mm, across. That makes the ball about 40% as wide as the hole: 42.67 ÷ 108 ≈ 0.40, our arithmetic.
What the hole can catch
When a putt reaches the front edge of the hole, the ground drops away and the ball starts to fall. If it’s moving too fast, it reaches the far side before it has dropped far enough. As physicist Rod Cross of the University of Sydney puts it, a ball that arrives too fast can bounce out of the hole when it strikes the opposite lip.
Brian Holmes worked out the limit in the American Journal of Physics in 1991. As cited by Hogan and Antali, a ball must travel at 1.626 meters per second or less to be captured, and Holmes’s theoretical predictions were consistent with experimental results. That is about 1.6 meters per second, or roughly 3.6 mph, our conversion.
Too fast
Under that limit, speed still matters. Writing about TrackMan putting data for GOLF.com, Luke Kerr-Dineen explained that the slower the ball is traveling as it enters the hole, the bigger the effective size of the hole becomes.
On a flat green rolling about 10 on the Stimpmeter, a putt hit hard enough to end a foot and a half past the hole makes the effective size of the hole about 25% smaller. Hit it hard enough to end about five feet past, and the hole plays 63% smaller, close to two thirds of it gone.
Two kinds of lip out
A fast ball that catches the edge can ride around the rim and spin away. In 2025, Hogan, of the University of Bristol, and Antali published the mechanics of the golf lip out in Royal Society Open Science. According to the University of Bristol, they showed there are two distinct types.
In a rim lip out, the ball’s center of mass never drops below the level of the green; the ball rides the rim and rolls away. In a hole lip out, the ball does fall in, swings around the inside of the hole like a pendulum, and can come back up to the rim and out onto the green.
Hogan’s advice, in the university’s release: “you need to aim as close to the centre of the hole as possible, and to arrive at the rim of the hole with little speed.”
The lumpy doughnut
So why not roll every putt in at the last moment? Dave Pelz, a former NASA scientist who went on to research the short game, found a problem around the hole: footprints. He called it the lumpy doughnut. As he described it to GOLF.com, footprints congregate within a radius of 6 feet of the hole, while the last 12 inches are almost footprint free.
By his count, a foursome leaves an average of more than 500 footprints on a green, and they can take up to 2 hours to spring back. To a rolling ball, he said, fresh footprints are like a curb is to a pedestrian crossing the street: the ball can “trip” on its way to the hole.
Even his own mechanical putter, the True Roller, could not make much more than half of 1,800 putts from 12 feet, Sports Illustrated reported in 1996, and Pelz said the reasons for missing mostly involve footprints, ball marks and the lumpy doughnut. A putt that is dying at the hole is at its slowest just as it crosses the doughnut. That is why Pelz wanted putts to roll past.
Seventeen inches
How far past? In tips first published in GOLF Magazine and republished by GOLF.com, Pelz said you must find a way to roll putts 17 inches past the hole when they miss, and that putts have a greater chance of going in at that speed, regardless of the length of the putt.
Put that next to the TrackMan numbers. Seventeen inches is about 1.42 feet, just under the foot and a half in that data. So at Pelz’s speed, the hole plays close to a quarter smaller than its full size. That is our reading of the two sources together.
That is the trade: you give up a little of the hole to keep the ball rolling through the footprints. Roll it five feet past and you’ve given up almost two thirds of the hole. Die it at the edge and you’ve left it to the footprints.
Uphill and downhill
Seventeen inches is a distance, but the hole only feels speed, and on a slope the same distance past means a different speed at the hole. In a study presented at the World Scientific Congress of Golf in St Andrews in 2016, Jonathon Sheppard, Paul Hurrion and Andrew Collinson rolled putts on a 3° slope through the center of the hole so that they would finish 0.30 m past, about a foot.
Putts straight down the slope were more than twice as slow at the front of the hole as putts straight up it. Uphill, the effective size of the hole was reduced by about 25%. Downhill, by only about 4%.
Gravity explains the gap. Uphill, gravity slows the ball, so it has to arrive faster to finish the same distance past. Downhill, gravity keeps it rolling, so it can arrive slowly and still get there.
Green speed
The “about 10” in the TrackMan numbers is a Stimpmeter reading. As Top 100 Teacher Erika Larkin explains for GOLF.com, the Stimpmeter was invented by Edward S. Stimpson, the 1935 Massachusetts Amateur champion. It is 36 inches long, with a notch 30 inches from the tapered end, and the ball releases when the bar is raised to 20 degrees.
You measure how far the ball rolls, in feet, with three balls in one direction and then three back the other way, and average the two. A slow green is about 8 to 8.5 feet; a fast one is 12 feet or more. What’s under that surface is in our article on what’s under a putting green.
On the course
A putt that stops short has no chance. One that arrives too fast shrinks the hole or lips out. Pelz’s answer sits in between: firm enough that a miss rolls about 17 inches past. And on a slope, those same 17 inches mean the ball reaches the hole harder going uphill and softer going downhill.
Illustrations by HYTON; ball motion, footprints and hole sizes are illustrative, and the figures marked as our arithmetic or reading are ours. Not affiliated with or endorsed by TrackMan, Pelz Golf, GOLF.com, Sports Illustrated, the University of Bristol, the Royal Society, the University of Sydney, the R&A or the International Golf Federation.
Sources
- S. J. Hogan and M. Antali, “Mechanics of the golf lip out,” Royal Society Open Science 12: 250907 (Nov. 5, 2025): putting constitutes 40–45% of all golf shots; citing B. W. Holmes (1991), a golf ball must travel at 1.626 m/s or less to be captured in the hole, and Holmes’s theoretical predictions were consistent with experimental results
- University of Bristol, “The physics behind the ‘lip out’ phenomenon in golf” (Nov. 5, 2025): two distinct types of lip out: the rim lip out, where the ball’s centre of mass does not fall below the level of the green, and the hole lip out, where it does, the ball undergoing a pendulum-like motion in the hole and able to return to the rim and back onto the green; John Hogan: aim as close to the centre of the hole as possible and arrive at the rim with little speed
- B. W. Holmes, “Putting: How a golf ball and hole interact,” American Journal of Physics 59, 129–136 (1991): as cited by Hogan and Antali (above) and by Rod Cross (below)
- Rod Cross, University of Sydney, Physics of Golf: if the ball arrives at the hole too fast, it can bounce out of the hole when it strikes the opposite lip; the problem was analysed by Brian Holmes (1991)
- Luke Kerr-Dineen, “How to make the golf hole bigger when you putt, according to science,” GOLF.com (Apr. 16, 2020): TrackMan data: the slower the ball enters the hole, the bigger its effective size; on a flat green rolling about 10 on the Stimpmeter, a putt hit to end 1.5 ft past makes the hole about 25% smaller, about 5 ft past 63% smaller
- Zephyr Melton, “10 brilliant short-game tips from teaching legend Dave Pelz,” GOLF.com (Mar. 26, 2025), from GOLF Magazine (2006): roll putts 17 inches past the hole when they miss; putts have a greater chance at this speed, regardless of putt length
- Luke Kerr-Dineen, “There’s a scientific reason why you’re missing putts,” GOLF.com (Mar. 24, 2021): quoting Dave Pelz: the lumpy doughnut is the congregation of footprints within a radius of 6 ft of the hole; the last 12 inches are almost footprint free; the average 500+ footprints a foursome makes take up to 2 hours to spring back; fresh footprints are to the ball like a curb to a pedestrian, and the ball can trip; Pelz recommended hitting putts 17 inches past
- “The Word According to Dave,” Sports Illustrated (Sept. 30, 1996): Pelz, a former NASA scientist; even with his mechanical putter, the “true roller,” he could not make much more than half of 1,800 12-foot putts; the reasons mostly involve footprints, ball marks and the lumpy doughnut
- J. J. Sheppard, P. D. Hurrion and A. R. Collinson, “An Investigation into Golf Ball Speed at Hole Entry,” World Scientific Congress of Golf, St Andrews (2016): 3° slope, putts finishing 0.30 m past the hole; putts directly down the slope were over two times slower at the front of the hole than those directly uphill; effective hole size reduced by about 25% uphill and only about 4% downhill
- International Golf Federation, Golf Definitions (2026): the hole must be 108 mm in diameter and at least 101.6 mm deep
- R&A, Rules of Equipment, Part 4: the diameter of the ball must not be less than 1.680 inches (42.67 mm)
- Erika Larkin, “What is stimp, and how do Stimpmeters work?” GOLF.com (Mar. 31, 2025): 36 inches long, notch 30 inches from the tapered end, ball releases at 20 degrees; average both directions; slow about 8 to 8.5 ft, fast 12 ft or more; invented by Edward S. Stimpson, the 1935 Massachusetts Amateur champion
- Our arithmetic and reading: 42.67 ÷ 108 ≈ 0.40 (about 40%); 1.626 m/s ≈ 3.6 mph; 17 in ≈ 1.42 ft, just under the 1.5 ft in the TrackMan data, so at Pelz’s speed the hole plays close to a quarter smaller; 63% is almost two thirds
Sources last checked October 2026.
Frequently asked questions
How hard should you hit a putt?
Dave Pelz's short-game research found that putts drop most often at a speed that would roll a miss about 17 inches past the hole, whatever the length of the putt. A putt that stops short can't go in, and one that arrives too fast makes the hole play smaller or lips out.
How fast can a putt be and still go in?
Brian Holmes calculated in the American Journal of Physics in 1991 that a ball must be traveling at about 1.6 meters per second or less, roughly 3.6 mph, to be captured by the hole, and his predictions matched experiments. Faster than that, it reaches the far side before dropping far enough and can bounce out off the opposite lip.
Does hitting a putt harder make the hole smaller?
Yes, in effect. TrackMan data published by GOLF.com shows that on a flat green at about 10 on the Stimpmeter, a putt rolling fast enough to finish 1.5 feet past makes the hole play about 25% smaller, and one fast enough to finish 5 feet past makes it play 63% smaller.
What is the lumpy doughnut?
Dave Pelz's name for the ring of footprints around a hole: they pack in within about 6 feet of it, while the last 12 inches are almost footprint free. By his count a foursome leaves more than 500 footprints on a green, which can take up to 2 hours to spring back, and a slow putt can trip on them.
Do uphill and downhill putts need different speeds?
Yes. In a 2016 study on a 3-degree slope, putts set to finish about a foot past the hole reached the front of the hole more than twice as fast uphill as downhill, and the hole played about 25% smaller uphill but only about 4% smaller downhill.
What does a Stimpmeter reading mean?
It's how far a ball rolls, in feet, after rolling off a 36-inch bar raised to 20 degrees, averaged over three balls in each of two directions. About 8 to 8.5 feet is slow; 12 feet or more is fast.
From this episode
Pelz’s 17 inches is on the How Hard to Hit a Putt golf towel, No. 4 ($20.99), which shows three putts: too soft, best speed and too firm. The Putt Speed golf mug, No. 4 ($20.99) has the big number on one side and the same putt-speed diagram on the other. Both are printed to order in the US with free US shipping. More designs from the series are in the Wear the Science collection.