What Is the Stimp in Golf?

Almost nothing in golf impacts your score more than the speed of the greens, yet the term most associated with it - Stimp - is often misunderstood. It’s not a secret code or a subjective feeling, it’s a specific, objective measurement that tells you exactly how fast the putting surfaces are on any given day. This article will break down what the Stimp is, how it's measured, and most importantly, how you can use that knowledge to conquer any green you face and stop three-putting.

What Is the Stimpmeter and What Does "Stimp" Mean?

In simple terms, the Stimp is the number, in feet, that a golf ball rolls after being released from a standardized ramp called a Stimpmeter. It's a direct measurement of green speed. A higher number means a faster green, and a lower number means a slower green. Simple as that.

The device itself, the Stimpmeter, is surprisingly basic. It's a 36-inch long V-grooved aluminum bar. Near one end, there's a small notch designed to hold a golf ball. When the bar is raised to a specific angle (about 20 degrees), gravity takes over, and the ball is released from the notch at a consistent velocity every single time. Where the ball comes to rest is measured, and this distance becomes the "Stimp reading."

It's important to understand that the Stimp is a measure of speed, not quality. A "fast" green isn't necessarily a "good" green, and a "slow" green isn't automatically a "bad" one. The goal for course superintendents isn't always to get the highest Stimp reading possible, but to provide smooth, consistent, and healthy putting surfaces suitable for the players at their facility.

A Quick History of Consistency

The Stimpmeter was invented in the 1930s by an avid amateur golfer named Edward S. Stimpson. After watching the 1935 U.S. Open at Oakmont, he was amazed by how lightning-fast and uniform the greens were. He realized there was no objective way to measure and replicate this quality. A green on one course might feel fast, but how did it compare to another? He crafted his wooden device to provide a standardized tool for measuring this consistency. However, it remained a niche tool until the USGA refined the design and officially adopted it in the mid-1970s, making it the an Ebel industry standard for course maintenance and tournament setup.

How Do You Get a Stimp Reading?

Taking an official Stimp reading is a precise process that course superintendents use to gauge their daily maintenance. It is designed to remove as much human variance as possible and get a true reflection of the surface's speed. Here’s how it works:

1. Find a Flat Spot: The superintendent finds a location on a practice green that is as level as possible. Any significant slope would skew the results.
2. Roll the First Ball: They place a golf ball in the notch of the Stimpmeter and slowly lift the end of the ramp. As soon as the ramp reaches that 20-degree angle, the ball rolls free. Three balls are rolled in one direction, and their stopping points are marked.
3. Roll in the Opposite Direction: To account for any subtle, unseen slope, they repeat the process from the stopping point of the first set of balls, rolling three new balls back toward the original starting point.
4. Measure and Average: They measure the distance of both rolls (from start to finish in each direction). The two distances are then averaged together to get the final Stimp reading for the day. For example, if the ball rolls 11 feet in one direction and 12 feet in the other, the Stimp reading is 11.5.

Understanding Stimp Numbers: From Slow to Professional Speed

So what do the numbers actually mean for your game? Understanding this range is the first step to adjusting your putting stroke on the course.

• Slow (Stimp 6-8): You'll typically find these speeds at many public courses. The grass is a bit longer, and the surface softer. On these greens, you need a firm, confident stroke to get the ball to the hole. Putts will roll out less and break less than on faster greens.
• Medium (Stimp 9-10): This is a common and very playable speed for most daily-fee courses and many private clubs. It provides a good balance where putts roll true without being outrageously sensitive to slope or stroke imperfections.
• Fast (Stimp 11-12): Now we're talking quick. These speeds are generally reserved for high-end private clubs and amateur tournaments. The putting surface feels slick, and the ball requires just a gentle tap to get it rolling. Breaks are much more pronounced, and downhill putts become treacherous.
• Tour-Level Fast (Stimp 13+): Welcome to the pros. Greens running at 13, 14, or even 15 are exceptionally rare and reserved for major championships like the U.S. Open and The Masters. At these speeds, a putting green can feel like putting on glass. Gravity is your biggest enemy on downhill putts, and you're often just trying to get the ball 'started' on the right line and let the slope do the rest.

What Factors Influence Green Speed?

A Stimp reading can change daily, or even throughout the day. It's not a static number. Several factors are constantly at play, most of which are managed by the course superintendent.

• Mowing Height: This is the number one driver of green speed. The shorter the grass is cut, the less friction there is, and the faster the ball will roll. Superintendents can "double-cut" or even "triple-cut" greens in the morning to increase their speed for a tournament.
• Rolling: Using a specialized heavyweight roller compresses the turf, making it smoother and firmer. This significantly speeds up the greens by reducing surface imperfections.
• Water: Moisture is a huge variable. Dry, firm greens are fast. Wet, soft greens are slow. This is why morning greens (covered in dew) are slower than afternoon greens after the sun has baked them out.
• Topdressing: When superintendents spread a thin layer of sand over the greens (a process that helps with plant health and surface smoothing), it will temporarily slow the greens down significantly until the sand settles into the canopy.
• Grass Type: Different grass species, like Bentgrass versus Bermuda grass, have different growth habits and leaf textures, which impacts the baseline speed.

How to Adapt Your Putting to Different Green Speeds

Knowing what the Stimp is becomes a superpower when you know how to apply it. The single most important thing you can do before any round is head to the practice green. Don’t just casually roll a few putts - be intentional.

Your Pre-Round Speed-Checking Routine:

1. Start with Lag Putts: Find a 30-40 foot putt. Forget the hole for a moment. Your only goal is to feel the stroke needed to get the ball to that distance. Hit several balls, focusing entirely on speed control. Does the ball die quickly, or does it seem to roll forever? This gives you your first, best feel for the day's speed.
2. Hit Uphill and Downhill Putts: Now notice the difference in stroke required. On fast greens, a downhill putt may require a backstroke that's just a few inches long. On slow greens, you'll still need to give it a solid rap.
3. Dial in the Short Ones: Once you have a feel for the pace, practice some 4-6 footers. This calibrates your brain for the amount of "hit" needed on those crucial scoring putts.

Adjusting Your Stroke: Fast Greens vs. Slow Greens

Coaching Tips for Fast Greens (Stimp 11+):

• Shorten Your Backstroke: Speed is mainly controlled by the length of your backswing. On fast greens, think "short and smooth." Any sudden, jerky motion will send the ball screaming past the hole.
• Trust the Break: Because the ball is moving slower over the ground for a longer period of time, it will be influenced more by slope. Dare to play more break than you think you need.
• Focus on Die Speed: Your goal isn’t to ram the ball into the back of the cup. For all but the shortest tap-ins, aim to have the ball "die" or just trickle into the front edge of the hole. This approach minimizes lip-outs and a makes any miss leave you a short second putt.
• Engage Your Big Muscles: Use your shoulders to control the putting stroke, keeping your hands and wrists quiet. This promotes a smoother, more repeatable pendulum motion.

Coaching Tips for Slow Greens (Stimp 6-8):

• Lengthen Your Follow-Through: On slow greens, you must be more aggressive. Fear of leaving it short is your enemy. Think about a longer, more assertive stroke with a full follow-through pointing toward the target.
• Don't Be Afraid to "Hit" It: You need to impart more energy. The pendulum stroke is still important, but a more aggressive acceleration through impact is required. Resist the urge to decelerate into the ball.
• Play Less Break: The ball is moving faster and has less time to be affected by the slope. A common mistake on slow greens is over-reading the break. Be more direct with your lines.

Final Thoughts

The Stimp reading is more than just a number for course agronomists, it’s a vital piece of information that can transform your putting. By understanding whether you're facing fast, medium, or slow conditions, you can make intelligent adjustments to your stroke, play the correct amount of break, and ultimately, drain more putts.

Knowing the conditions is a major part of sharpening your on-course strategy. At Caddie AI, we help you translate this kind of course knowledge into better decisions. By building a personalized strategy for every hole, our recommendations instantly consider a wide number of factors that you’re dealing with. So whether it’s club selection for an approach to a lightning-fast green or help reading a tricky chip, you can get instant advice that helps you play with more confidence and avoid the big mistakes that lead to three-putts.