How to really measure green speeds

Golf Ball

Greens are primarily defined by one thing — speed. Sure, grass type, grass length, slope, surface hardness, surface evenness, rain frequency and timing, etc. all play into how a green or set of greens play on any given course. But, at the base level, all those factors primarily affect the speed of the green. And as it turns out, it’s really hard to measure the speed of the green independently of the slope. Even though a plethora of factors go into ascertaining a green’s speed, the slope is the most constant and consistent variable, yet it still presents the largest impediment to measuring said greens’ speeds.

Let me explain.

In an effort to standardize green speed readings, the USGA in 1976-77 distributed Stimpmeters, the measurement device for determining such readings, to approximately 1,500 member golf courses in 36 states to measure the ball-roll distances on greens. These distances were then categorized and standardized for member play vs. tournament play, according to a rough table published by the USGA:


By determining and standardizing the green speeds across USGA member and tournament courses, the USGA was able to set baseline measurements for superintendents to abide by/aim for, depending on the nature of the course(s) they oversaw. But, there was one huge obstacle…

Green speed readings only work on level ground.

As anyone who has played or managed a number of courses can tell you, few greens have a large enough flat area to perform a Stimpmeter reading as intended. Because of that, it often necessitates the reading professional to either skip holes, or entire clusters of holes. For many courses, the climate, frequency of play, absence of rain, or any number of factors will determine how fast a green is. But, the number one way to amplify green difficulty is to design a course with ample undulations and slopes to confront players.

In those situations, Stimpmeters were useless for a number of years.

Recently, a group of agronomists and mathematicians have figured out how to calculate green speed despite slopes therein. Specifically, A. Douglas Brede, Ph.D. penned a definitive report on how to account for slope in green speed readings. At the simplest level, you measure the green rolling balls on the downslope, the upslope, and as flat an area as can be found, and then average them all using a mathematical formula:


And there you have it — a true, slope-adjusted green speed. Now, using the formula can be a little more complex than just plugging in numbers, so definitely check out the report linked to above for the more specific breakdown/instructions.


All of this is to say, when it comes to rating greens and their speeds, we all know finding enough flat ground on the individual surfaces can be hard — especially when you’re expected to produce 18 green readings per course. But, by utilizing the newer, slope-adjusted formats, you can more easily and accurately give players and pros alike an insight into your greens.


If, for any reason, you want to see more of the math behind the madness, be sure to give us a call or shoot us an email. At ezLocator, we’re always hoping to help a client (or soon-to-be one) get the best out of their course(s).