Free tool
Putt break calculator.
Enter the putt's length, the slope and the green speed. The calculator rolls a simulated ball over that slope, finds the line that drops, and tells you where to aim.
Aim
11.0 in
left of the hole · 2½ cups
Plays like
10.0 ft
Plumb bob shows
3.2 in
Seen from above, sideways scale exaggerated. Yellow: the ball's path. Thin line: the start line to the aim point.
How to use it
- Length: pace it off. One normal step is about 3 feet for most adults.
- Side slope: how steeply the green tilts across your line. Use the guide below if you don't know the number.
- Which way: the putt breaks toward the low side. See how to tell which way a putt breaks.
- Uphill or downhill: the slope along the line. Downhill putts break much more.
- Green speed: the Stimp reading, if the club posts one. Most public courses run 8–9, private clubs 10–11. Or measure it yourself.
Then start the ball at the aim point, at a pace that would finish the set distance past the hole. The line only works at that pace: a softer putt breaks more, and a firmer one less.
How steep is the green? A slope guide
| Slope | What it looks and feels like |
|---|---|
| 0–1% | Looks flat. Water drains slowly. You can't feel it standing still. |
| 1–2% | Barely visible. You feel it through your feet standing across the line. |
| 2–3% | A typical hole location on a sloping green. Clear from a distance. |
| 3–4% | Obvious. About the steepest a hole is cut on a fast green. |
| 4%+ | Too steep to hold a hole on quick greens; a ball struggles to stop. |
Putt break chart
How far outside the hole to aim, in inches, on a flat-along-the-line putt at Stimp 10, finishing 17 inches past. Cups are hole-widths (4¼ in).
| Length | 1% slope | 2% slope | 3% slope |
|---|---|---|---|
| 3 ft | 1.1 in (½ cups) | 2.2 in (½ cups) | 3.3 in (1 cups) |
| 5 ft | 2.2 in (½ cups) | 4.5 in (1 cups) | 6.9 in (1½ cups) |
| 8 ft | 4.1 in (1 cups) | 8.3 in (2 cups) | 12.7 in (3 cups) |
| 10 ft | 5.4 in (1½ cups) | 11.0 in (2½ cups) | 16.9 in (4 cups) |
| 15 ft | 8.9 in (2 cups) | 18.0 in (4 cups) | 27.6 in (6½ cups) |
| 20 ft | 12.4 in (3 cups) | 25.2 in (6 cups) | 38.7 in (9 cups) |
| 30 ft | 19.7 in (4½ cups) | 40.0 in (9½ cups) | 61.4 in (14½ cups) |
Adjust for speed and grade: at Stimp 8 the same putts break about 20% less, and at Stimp 12 about 21% more. A 2% downhill putt breaks about 39% more, and a 2% uphill putt about 22% less.
How it works
The calculator is the physics model from our technical note, the physics of a breaking putt, running in your browser. A ball rolls without slipping, so gravity pulls it down the slope at 5/7 of g times the slope. Rolling resistance slows it along its direction of travel, at a rate set by the green's Stimp reading. The calculator launches simulated putts and adjusts the start line and speed until the ball rolls through the centre of the hole at your chosen pace. The aim point is where that start line passes the hole.
Three results surprise most golfers:
- Break grows faster than distance. A 20-footer breaks more than twice as much as a 10-footer on the same slope.
- Most of the break happens near the hole, where the ball is slow: about two-thirds of it in the last third of a 10-foot putt.
- Plumb bobbing shows far less break than you need. The "plumb bob shows" figure is what a perfect plumb-bobber would see: the right direction, a fraction of the amount. See how to plumb bob a putt.
If your putts keep finishing below the hole, you're not alone: studies find golfers read about a quarter of the real break. See why you miss on the low side.
What it doesn't know
- Real greens aren't flat planes. The calculator assumes one steady slope. Greens curve, and double breakers need a read of each section.
- Grain, wind and wet grass aren't modelled. Grain matters most on Bermuda greens.
- You still have to know the slope. Guessing the slope is the hard part, and it's where most misreads start.
FAQ
How do you calculate the break of a putt?
Break depends on the side slope, the putt's length, the green speed, whether it runs uphill or downhill, and the pace. This calculator rolls a simulated ball over the slope with those inputs and finds the start line that holes it. For example, a 10-foot putt across a 2% slope at Stimp 10 needs about 11.0 inches of break.
How much does a putt break per percent of slope?
Roughly in proportion to the slope, but not to the distance. At Stimp 10, a 10-footer breaks about 5.4 inches on 1%, 11.0 on 2% and 16.9 on 3%. Break grows faster than the length of the putt.
How do I know the slope of a green in percent?
Most hole locations sit on 1–3% slopes. 1% is barely visible, 2% is a gentle slope you can feel through your feet, 3% is obvious, and 4% is about the steepest a hole is cut on a fast green. A green-reading app can measure it for you on the practice green.
Do faster greens break more?
Yes. The same 10-foot putt on a 2% slope needs 8.7 inches of break at Stimp 8 and 13.3 inches at Stimp 12.
Do downhill putts break more?
Yes, much more. The same 10-footer across a 2% side slope needs 15.2 inches running 2% downhill and 8.6 inches running 2% uphill.
Can I use a putt break calculator in a tournament?
No. Using a device to measure or interpret slope during a round breaches Rule 4.3 of the Rules of Golf. Use it to practise and to learn what slopes do, then read with your eyes and feet in competition.
For practice and friendly rounds. Using a device to read greens during a competition round breaches Rule 4.3: see are green reading apps legal?