Do fast greens break more? Yes, and here's how much

Yes, fast greens break more, and slow greens break less. The break goes up roughly in step with the Stimp: a 10-foot putt across a 2% slope needs about 8.7 inches of break at Stimp 8 and 13.3 inches at Stimp 12, half as much again.

The slope hasn't changed. What changed is how softly you hit the ball and how long it spends rolling across the slope. This post has the numbers by green speed, the reason behind them, and a simple way to adjust your reads when you play a faster or slower course than you're used to.

How much more fast greens break

We ran a 10-foot putt across a 2% side slope, a typical hole location, through Plumb Bob's putt simulator. It models a ball rolling over a tilted green, slowed by the grass, hit at a pace that would finish about 17 inches past the hole. Here's how far outside the hole you need to start it at each green speed:

From Stimp 7 to Stimp 14 the green speed doubles, and so does the break. Each extra foot on the Stimpmeter adds a bit over an inch of break on this putt.

The pattern holds at every length. Here's the same 2% slope at 5 and 20 feet:

A 20-footer that needs under two feet of break on a medium green needs two and a half feet on a very fast one. You can try your own putts in the putt break calculator.

The rule of thumb: break scales with the Stimp

You don't need the table on the course. Use a ratio:

New break ≈ your usual break × (new Stimp ÷ usual Stimp)

If your home greens run about 9 and you play a club running 11, multiply your normal reads by 11 ÷ 9, about 1.2. Play a fifth more break. Going from 8 to 12, multiply by 1.5. Going from 10 down to 8 on a wet or shaggy day, play about a fifth less.

Against the simulator, this ratio lands within a few percent on level putts across a side slope. It runs a little short on downhill putts and a little long on uphill ones, which is the next section.

You'll see the claim online that you should "double the break" on greens running 12 or faster. That's only right if you're coming from greens around 6. From a typical public course at 9, Stimp 12 is about a third more break, not double. Where the big multipliers do show up is downhill.

Downhill on a fast green: where the break explodes

Green speed and downhill slope pile on top of each other. Here's the 10-foot putt across 2% again, now also running 2% uphill or 2% downhill:

Compare the corners. An uphill putt on a medium green needs 7 inches. The same putt downhill on a very fast green needs 20, almost three times as much. That's the putt where "double or triple the break" is true, and it's the putt where most low-side misses come from.

The reason is that on a fast green the grass barely slows the ball, so gravity becomes a big share of what decides its speed. Downhill, gravity keeps the ball rolling slowly for longer. Uphill, it stops the ball sooner, and the green speed matters less. (For which way these putts turn, see how to tell which way a putt breaks.)

Why fast greens break more

It comes down to time on the slope. The side slope pushes the ball sideways the whole time it's rolling, and how far that push moves the ball grows with the square of the time.

On a fast green, the grass slows the ball more gently. To get the same 10-foot putt to finish 17 inches past, you hit it softer. With the simulator's physics, the ball leaves the putter about 18% slower at Stimp 12 than at Stimp 8. It then takes about 2.5 seconds to reach the hole instead of about 2.1. That's around 22% more time, and because the sideways drift grows with time squared, about 50% more break.

Do that sum for any two green speeds and the time squared works out in proportion to the Stimp. That's why the ratio rule works.

It also explains three things golfers notice:

• Putts break most near the hole. The ball is slowest there, so each inch of roll takes longest.
• Firm putts break less. Hit it harder and it spends less time on the slope. On a fast green, though, firm putts that miss run a long way past.
• Slow greens break less. A firm putt on a shaggy green crosses the slope quickly.

Your eyes don't see the speed

This is the part that catches struggling golfers. When you read a putt, you're reading the slope: by eye, with your feet, or with a plumb bob. The slope is the same on Tuesday's slow green as on Saturday's fast one. So your read comes out the same, and the putt breaks more than you played.

The simulator shows it. A perfect plumb-bob read of that 2% putt shows the same 3.2 inches at every Stimp, from 7 to 14. The real break runs from 7.6 to 15.7 inches. Whatever method you use, the green-speed correction is a separate step that you have to add yourself. (More on what a plumb bob does and doesn't tell you in plumb bob putting.)

Golfers already under-read break badly on greens they know. In Dave Pelz's testing, golfers of every level played about a quarter of the true break, as we cover in missing putts on the low side. A faster green than usual makes that gap wider.

How to adjust your reads on fast greens

1. Know the speed before you tee off. Ask the pro shop if they post a Stimp reading, or measure the green speed on the practice green with a stopwatch. You need a number for the ratio rule, and you need to know which way to move from home.
2. Read the slope as normal, then scale it. Make your usual read, then multiply by the speed ratio. On a green two Stimp faster than home, that's roughly a fifth to a quarter more break.
3. Add extra on anything downhill. On a fast green, a downhill putt with side slope needs far more than the ratio says. Start it higher than feels right and let it die toward the hole.
4. Roll three breaking putts before the round. Pick a 10-footer with obvious break on the practice green. Read it, play it, and see which side it misses. If it misses low, play more break all day.
5. Pick pace first. Break depends on pace, so decide how far past you want the ball to finish before you choose the line. On fast greens, a dying pace near the hole breaks the most and leaves short comebacks. See how hard to hit a putt for pace by distance.
6. Watch for grain. On Bermuda greens, putting down grain plays faster and breaks more, and into grain plays slower. Grain can make one side of a green behave like a different Stimp. See how to read grain on greens.

Plumb Bob is a green reading app for iPhone, and it's built to fix exactly this gap. It reads the slope with the camera (most precisely on iPhones with LiDAR, and it works without), and applies the green speed to it. It measures slope, not grain. Use it on the practice green and in friendly rounds to see how much more fast greens break than you'd play, then carry that correction into competition, where devices that read greens aren't allowed under Rule 4.3. You get 3 free reads, then Plumb Bob Pro is $9.99 a month or $59.99 a year, with a free week for new subscribers.

FAQ

Do fast greens break more or less?

More. A faster green slows the ball more gently, so you hit it softer and it spends longer rolling across the slope. On a 10-foot putt across a 2% slope, Plumb Bob's simulator gives 8.7 inches of break at Stimp 8 and 13.3 inches at Stimp 12.

Do slow greens break more or less?

Less. On a slow green you hit the ball firmer to get it to the hole, so it crosses the slope faster and turns less. The same 10-footer needs 7.6 inches of break at Stimp 7 against 11.0 at Stimp 10.

How much more do fast greens break?

Roughly in proportion to the Stimp. Multiply your usual break by the new Stimp divided by your usual Stimp. Going from 9 to 12 is about a third more break, and from 7 to 14 is double. Downhill putts on fast greens break even more than that.

Do wet greens break less?

Usually, because wet greens usually roll slower, and slower greens break less. How much slower depends on the grass and how wet it is, so roll a few balls or time one to check the speed, then scale your reads down to match.

Do downhill putts break more on fast greens?

Yes, much more. At Stimp 12, a 10-foot putt across 2% that also runs 2% downhill needs about 20 inches of break, against about 10 inches when it runs 2% uphill. Fast greens and downhill slopes multiply each other.

Should I hit putts harder on fast greens to take out the break?

Not usually. A firmer putt breaks less, but on a fast green a miss runs well past the hole and leaves a long comeback. It's better to play more break at a pace that finishes about 17 inches past, and to keep firm putts for short, straight-ish ones.