Pattern length minus 31 gives your target breakpoint board.
The Rule of 31 is a quick way to estimate where your ball should finish its trip through the oil. Take the length of the oil pattern in feet and subtract 31. The answer is the board where the ball should be at the end of the pattern, your breakpoint.
It is a starting point, not a guarantee. Ball, surface, speed, rev rate and lane condition all move the real number. But it gets you to a sensible target on the first shot instead of guessing.
A tournament sheet says the pattern is 40 feet. 40 minus 31 is 9, so you want the ball finishing around board 9, near 37 to 40 feet down the lane.
Now work backward. Pick a starting board and a target at the arrows so the ball arrives at board 9 at the end of the oil. If the ball is early, move your feet or target to give it more room. If it is late or hanging, give it a shorter path.
Same math for the PBA animal patterns:
| Pattern | Length | Breakpoint |
|---|---|---|
| Cheetah | 35 ft | Board 4 |
| Viper | 36 ft | Board 5 |
| Chameleon | 39 ft | Board 8 |
| Scorpion | 42 ft | Board 11 |
| Shark | 48 ft | Board 17 |
Type your pattern length into the Rule of 31 calculator and it gives the target breakpoint. The same page has the 3-6-9 spare adjustment tool.
Also see the PBA animal patterns guide, the lane transition guide for what to change as the oil breaks down, and how to hook a bowling ball.
The rule assumes a typical pattern and a ball that reads the lane in a normal way. On a house shot with heavy oil in the middle you are usually not trying to hit a precise breakpoint at all. On flat sport patterns, small errors matter much more. A coach watching your ball motion can tell you how far to trust it for your game.
Book a session with a 2009 PBA Scorpion Champion. In person at Strike Force Lanes in Greenfield, or by video from anywhere. See lessons for Indianapolis, Carmel and Fishers, or virtual video lessons.
Text Mike (702) 701-1494Subtract 31 from the oil pattern length in feet. The result is the board where your ball should finish its path through the oil, your breakpoint.
40 minus 31 equals 9, so the target breakpoint is around board 9.
It is a rough guide. House shots are built to forgive misses, so it matters most on sport and challenge patterns.