Every golfer has heard a course called “fast” or “slow” — and most have stood over a putt that ran out 20 feet past the hole on a green they thought they had measured correctly. The number behind all of that is green speed, and the device that produces it is the Stimpmeter. Understanding what a Stimp reading really represents — and what it does not — will change how you read, stroke and trust your putts on any course.
What Is a Stimpmeter?
The Stimpmeter is a simple aluminum or steel ramp about 36 inches long with a small notch cut near one end. A golf ball is placed in the notch, the ramp is slowly raised until the ball releases on its own, and the ball rolls down the ramp and out onto the green. The distance the ball travels, measured in feet, is the green speed for that putt. The device was invented in 1935 by an amateur named Edward S. Stimpson Sr., who was watching the 1935 U.S. Open at Oakmont and grew suspicious that the greens were much faster than they should be. He wanted a way to prove it.
The USGA refined and standardized Stimpson’s original design in the mid-1970s and began using it to publish green-speed guidelines for major championships. Today every serious golf course superintendent in the world owns one, and the readings drive maintenance decisions about mowing height, rolling, top-dressing and irrigation throughout the season.
Despite the technical-sounding name, the Stimpmeter is one of the least technical pieces of equipment in golf. It has no electronics, no calibration screws and no moving parts. Its genius is that the ramp’s angle is fixed by gravity: when the ball releases from the notch, it always leaves the ramp at the same speed regardless of who is using the device. That is what makes Stimp readings comparable from course to course.
How a Stimpmeter Measures Green Speed
The standard testing protocol is straightforward but specific. The superintendent finds a flat section of green — typically a 10-foot by 10-foot area where any slope is less than one percent. Three balls are rolled in one direction, and the average distance is measured. Then three balls are rolled back along the same path in the opposite direction. The two averages should be within six inches of each other. If they are not, the ground is not truly level and a new spot is selected.
The final Stimp reading is the average of those six rolls — three in each direction — expressed in feet. So a green that produces an average roll of 11 feet 4 inches has a Stimp reading of “eleven four”, or simply “11.4”. Some superintendents repeat the test on three or four different greens around the course and average the results to get a representative number for the whole course on that day.
It is worth noting that the Stimpmeter measures roll-out distance, not ball speed at the moment of contact. That distinction matters because the same initial ball speed will roll out very different distances depending on what the green is doing — moisture, grain, grass length, surface compaction and temperature all affect it. The Stimp number captures all of those variables in one easy-to-communicate figure.
What Stimp Readings Actually Mean
Most everyday golfers have no idea what a Stimp number translates to in real-world terms. Here is a working scale that holds up across most of the United States:
7 to 8 feet — slow. Most municipal courses live in this range, especially on Bermudagrass greens during the cooler months. Putts feel like they need to be “hit” rather than “stroked”, and three-putts from outside 30 feet are common because the ball does not release.
9 to 10 feet — medium. A well-maintained private club in the U.S. typically sits here for daily play. Distance control becomes much more about feel and pace than effort. This is also the range where reading the break starts to matter as much as starting line.
11 to 12 feet — fast. Member-guest events at premium clubs and most regular PGA Tour stops fall here. The greens reward smooth, accelerating strokes and punish any deceleration. Lag putting becomes a serious skill, and downhill putts above the hole feel unnervingly fragile.
13 feet and above — championship. This is U.S. Open Sunday, Masters Sunday, and the occasional brutal day at Augusta National in April. The ball seems to drift on its own once it stops accelerating. Routine four-footers become genuinely difficult. Sub-par putting requires almost perfect speed control.
Tournament Green Speeds vs. Local Course Speeds
One of the most damaging mistakes amateur golfers make is assuming the greens they see on television are the same as the ones at their home course. They are not. Augusta’s greens during the Masters are typically rolled to 13–14 feet for the week. Pinehurst No. 2 during the 2024 U.S. Open ran a similar speed in the practice rounds. Shinnecock Hills has historically been pushed above 14 in mid-week with the wind down.
For comparison, your typical Saturday morning round at a busy public course in July is being played on greens that read between 8 and 10. That difference of 4 to 6 feet sounds small, but in practice it is enormous. A 20-foot putt struck the same way on a 9-foot green and a 14-foot green will finish more than 30 feet apart in terms of roll-out behaviour. This is why pros routinely take Monday and Tuesday of tournament week purely to “find their speed” — they need to recalibrate before competition begins.
If you only ever play one home course, your putting feel is calibrated to that course’s speed. The moment you travel — to a destination resort, a faster private course, or a slower municipal layout — your distance control will struggle for at least the first nine holes. Recognising this in advance is half the battle.
What Affects the Reading on Any Given Day
Even the same green can read very differently from morning to afternoon. Superintendents track several variables that swing Stimp numbers, sometimes by an entire foot in a single round.
Mowing height and frequency
Greens are typically mown at heights between 0.090 and 0.140 inches. Dropping the height by even five-thousandths of an inch can add half a foot of Stimp. Major championship venues frequently double-cut and roll greens daily for tournament weeks.
Moisture
A morning watering or overnight rain can slow greens by a full foot or more. As the surface dries through the day, greens speed up. This is why afternoon putts on the same hole behave very differently than the same putt at 7am.
Grass type and grain
The type of turf matters enormously. Bermudagrass versus bentgrass behaves very differently — Bermuda has prominent grain that can push or hold a ball, while bentgrass produces a more uniform roll. Grain becomes a major factor below 10 on the Stimp scale, and almost disappears at championship speeds.
Wind and temperature
A breezy day pulls moisture out of grass blades faster, speeding greens up. A cool, humid morning slows them down. Some courses publish a different “expected” Stimp number depending on whether the round is in the early or late wave.
How Stimp Reading Should Change Your Putting Approach
Most golfers fixate on read — how much the putt is going to break. But on faster greens, speed becomes the dominant variable, and break is a consequence of speed. A putt struck firmly takes less break. The same putt rolled at “dying-into-the-hole” speed takes a great deal more. On a 13-foot green, the difference between those two pace choices is enormous; on a 9-foot green, it is much smaller. That is why structured green-reading systems emphasise pacing the read to a specific speed assumption.
Three practical adjustments help every golfer use Stimp information well:
1. Establish your reference speed on the practice green. The practice green is intentionally maintained at the same speed as the course greens that day. Spend the first five minutes of any warm-up rolling 30-, 40- and 50-foot putts to feel the pace before you start working on alignment or stroke mechanics.
2. On unfamiliar fast greens, plan to leave putts short. The natural tendency is to be aggressive in the first few holes of a new course. On fast greens, aggression turns three-putts into four-putts. A practical heuristic: aim to leave longer putts a foot short of the hole rather than a foot past it until you have seen the speed for at least nine holes. This approach pairs with general distance-control fundamentals.
3. Read downhill putts differently from uphill putts on fast greens. Above the hole on a Stimp-13 green, a putt that breaks 18 inches at “tournament pace” can break four to five feet if struck slightly soft. Above 12 feet on the Stimp scale, downhill break almost always increases. Below 10 feet, the difference between hard and soft strokes is much smaller. Pros adjust their starting lines aggressively for downhill putts when the Stimp climbs; amateurs almost never do, which is one of the largest sources of three-putts at faster courses.
Better lag putting is largely a function of speed calibration, which is why avoiding three-putts is so closely tied to understanding green speed, not just reading break.
Why Knowing the Number Beats Guessing
Many courses now post the day’s Stimp reading on the first tee, the practice green or the scorecard. If yours does, read it before you warm up. If it does not, ask the pro shop. Most superintendents take readings every morning, and the staff usually knows the number. Walking onto greens with a real figure in mind — rather than the vague impression of “fast today” — changes how you approach every long putt.
The Stimpmeter is one of the simplest measuring devices in sport, but the number it produces silently controls more strokes than any other course condition. A round played on a 9-foot green and the same round played on a 13-foot green are, statistically, two different games. The faster you learn to translate a Stimp reading into a putting plan — pace, line, aggression and lag length — the faster your putting will travel with you to any course in the world.
