Green Speed Chart: What Stimp Actually Does to Your Putt

Roll distance scales directly with the stimp reading, because that is what the reading measures. Make the stroke that holes a 20-footer on a stimp 10 green, and on a stimp 12 green the same stroke sends the ball 24 feet.

The bracket is how far past or short of the hole you finish. Read down your usual green speed to see what your calibration is worth somewhere else — a member at a stimp 9 club playing a stimp 12 resort green leaves every long putt a third of the way past.

This is the part worth internalising. A Stimpmeter measures a flat green. Almost no putt is on a flat green.

Gravity adds to or subtracts from the friction slowing the ball, so a slope does not nudge the effective speed — it transforms it. On a green stimping 10:

A 2 percent downslope — barely visible, the kind you walk over without noticing — plays like stimp 15.6. No golf course on earth maintains greens that fast. At 3 percent you are putting on the equivalent of stimp 21.

The same slope uphill drops you to about 7.4, slower than a municipal course in the wet. That is why the uphill-downhill difference on the same green feels like two different sports, and why "the greens are quick today" is much less useful information than the slope you are actually standing on.

Faster greens break more, because the ball travels more slowly for longer and gravity has more time to work on it. The working formula is slope percent x distance in feet x stimp / 20, which gives inches of break. At stimp 10 that reduces to the old caddie rule of half the slope percentage in inches per foot.

Break on a 2 percent slope:

A 20-footer that breaks 16 inches at your home club breaks two full feet on a tournament-speed green. Aim at the same spot and you miss on the low side every time — which is the single most common miss in amateur putting.

Push the arithmetic far enough and it produces a hard limit. When the slope exceeds the rolling resistance of the surface, gravity beats friction and the ball does not come to rest at all.

This is not a curiosity — it is the constraint that governs where a superintendent can cut a hole. At stimp 8 there is room to use a 6 percent shoulder. At stimp 13 anything past 4.3 percent is unusable, which is why greens get demonstrably flatter in the hole locations as tournament week goes on, and why you occasionally see a ball on television trickle away from a stopped position.

It is also the honest answer to why your club cannot simply run the greens at 13 because it sounds impressive. Speed removes pin positions.

The arithmetic is clean; greens are not. Four things move the real number.

Water. Morning dew or a recent rain can take two or three points off the effective speed, and no pin sheet will tell you.

Grain. On bermuda especially, a putt into the grain plays materially slower than the same putt down-grain on the same green. Look at the sheen: shiny is down-grain and fast.

Wind. On very fast greens a strong wind genuinely moves the ball, which is why tournaments slow greens down when it blows rather than risk balls oscillating at rest.

Slope in two directions. The tables treat downhill and side-slope separately. A putt that is both is worse than either, because the extra speed from the fall line increases the time the side-slope has to act.

Use the charts to calibrate, then trust your eyes. For the rest of the distance picture, our wind chart and temperature chart cover the full-swing side.