What horizontal break means
Horizontal break measures side-to-side movement caused by spin. Like induced vertical break, it compares the real path of a pitch with the path of a spinless ball thrown the same way. Gravity does not pull sideways, so the horizontal number comes from spin and seam effects. Most tracking systems report it in inches and label the direction as arm side or glove side, or as a positive or negative number.
Arm side and glove side flip with handedness. For a right-handed pitcher, arm-side break moves toward a right-handed hitter and glove-side break moves away from one. For a lefty, it is the reverse. Using arm side and glove side lets you compare pitchers without flipping signs. Sinkers, two-seamers, and changeups break arm side. Sliders, sweepers, cutters, and most curveballs break glove side.
How much horizontal break is good depends on the pitch. A sinker or changeup usually wants more arm-side run. A sweeper is built to move a lot to the glove side. A gyro slider or cutter often moves only a few inches, and that is by design. Horizontal break also matters in pairs. A sinker that runs one way and a sweeper that breaks the other way make each other harder to hit.
Video explanation
Jake Fishman, PitchLab’s co-founder and CEO, pitched in the major leagues for the Miami Marlins. Here he explains horizontal break and what it means for your pitching.
What affects horizontal break
Arm slot
Lower, more sidearm slots produce more horizontal movement on fastballs and changeups. Higher slots tend to produce more vertical movement.
Spin axis
The more the axis tilts from pure backspin or topspin toward sidespin, the more of the movement goes sideways.
Spin efficiency
Sidespin only moves the ball if it is active spin. A slider with a lot of gyro moves only a few inches, even with high spin.
Spin rate
More active spin produces more sideways force. This matters most on sweepers, which rely on spin to cover a lot of ground.
Seam effects
Sinkers and changeups often get extra arm-side movement from how the seams disturb the airflow. This can add movement beyond what spin alone predicts.
Velocity
Slower pitches spend more time in the air, so the same spin has more time to move them. That is part of why sweepers and changeups can show large break numbers.
What’s a good horizontal break?
| Pitch type | Average | Good | Great | Excellent |
|---|---|---|---|---|
| Sinker (arm side) | 15 | 16.5 | 18 | 19+ |
| Changeup (arm side) | 14 | 15.5 | 17 | 18+ |
| Sweeper (glove side) | 15 | 16.5 | 18 | 19+ |
More break is better for sinkers, changeups, and sweepers, measured toward the side named in the row. Curveballs are left off because their best sideways number depends on the shape you want. A 12-6 curve moves mostly down, and a slurve moves more sideways.
How PitchLab measures it
PitchLab measures horizontal break on every pitch and shows it with induced vertical break, so you can see each pitch's full movement shape. Trends across sessions show whether your run or sweep is growing.
Horizontal break FAQs
How do you measure horizontal break with your phone?
Set an iPhone 12 or newer on a tripod about 2 ft behind the pitcher, facing home plate, and start a session in PitchLab. PitchLab measures horizontal break on every pitch and shows it with induced vertical break, so you see the pitch’s full shape.
Is there an app that measures horizontal break?
Yes. PitchLab measures horizontal break with just an iPhone and a tripod, and plots every pitch on a movement profile. PitchLab is free to start.
What’s the best app for adding run or sweep?
Use an app that shows horizontal break on every pitch and plots your pitch types on a movement chart, so you can see how far each one moves and whether a change is working. PitchLab does this with an iPhone.
What is a good horizontal break for a sinker?
In MLB, sinkers average about 15 inches of arm-side break. About 16.5 inches is good, 18 is great, and 19 or more is elite. High school and college sinkers usually show a few inches less, so compare within your level and velocity.
What is the difference between arm-side and glove-side break?
Arm-side break moves toward the pitcher's throwing-arm side. Glove-side break moves toward the glove side. For a right-handed pitcher, arm-side pitches move in on a right-handed hitter and glove-side pitches move away. The same labels work for lefties, which makes comparisons easier.
How much horizontal break does a sweeper have?
MLB sweepers average around 15 inches of glove-side break, and the best pass 19 inches. A sweeper has little vertical movement, so most of its break goes sideways. It works best against same-side hitters because it breaks away from them.
Is more horizontal break always better?
No. More run helps sinkers and changeups, and more sweep helps sweepers. For four-seamers, cutters, and gyro sliders, a smaller number can be the goal. What matters most is how each pitch moves compared with your other pitches.
