Table of Contents
What Is a Stimpmeter?
A stimpmeter is a simple aluminum bar used to measure the speed of putting greens. Invented by Edward Stimpson in 1935 and adopted by the USGA in 1978, it provides a standardized measurement of green speed. The device is a 36-inch inclined ramp that releases a golf ball at a consistent velocity. The distance the ball rolls on the green (in feet) is the stimpmeter reading.
Higher stimpmeter readings indicate faster greens. Most recreational courses maintain stimpmeter speeds between 8 and 10 feet, while professional tournaments typically play at 11 to 14 feet. Augusta National during The Masters often reaches 13-14 on the stimpmeter.
Green Speed Formulas
The constant K accounts for friction and ball behavior, typically around 4.0 for standard putting conditions. The break formula shows that break increases with the square of putt distance, which is why long putts on sloped greens break significantly more than short putts.
Green Speed Categories
| Category | Stimp Reading | Typical Setting |
|---|---|---|
| Very Slow | Below 7.0 | Poorly maintained, wet conditions |
| Slow | 7.0 - 8.5 | Municipal/public courses |
| Medium | 8.5 - 10.0 | Average private clubs |
| Fast | 10.0 - 11.5 | Well-maintained clubs |
| Very Fast | 11.5 - 13.0 | Tournament conditions |
| Extreme | 13.0+ | Major championships |
Slope Effects on Speed
Slope dramatically changes effective green speed. A 2% downhill slope on a green reading 10 on the stimpmeter can make the putt play like a 14-stimp green. Conversely, the same slope uphill makes the green play like an 8-stimp surface. This is why reading slopes accurately is one of the most valuable putting skills.
On sidehill putts, the ball breaks toward the low side. The amount of break depends on slope percentage, putt distance, and green speed. Faster greens produce more break because the ball is rolling more slowly relative to the green surface, giving gravity more time to pull it downhill.
Frequently Asked Questions
How do I read green speed without a stimpmeter?
Roll a ball from a consistent position and measure how far it travels. You can also observe how the ball reacts to a standard lag putt. If a 30-foot putt requires barely touching the ball, the greens are very fast. Practice greens usually have similar speed to the course greens on any given day.
Does green speed change during the day?
Yes. Greens are typically fastest in the late morning after dew has dried and the grass has been mowed. They slow down in the afternoon as grass grows slightly and foot traffic compacts the surface. Morning dew can slow greens by 1-2 feet on the stimpmeter.
How does grain affect green speed?
Bermuda and other warm-season grasses have significant grain (the direction grass blades grow). Putting with the grain is faster, while putting against the grain is slower. The difference can be 1-3 feet on the stimpmeter. Grain typically grows toward the setting sun and toward water drainage.