What gyro degree means
Every pitch spins around an axis. Picture a skewer pushed through the ball along that axis. If the skewer points across the ball's path, like the axle of a rolling wheel, all of the spin is backspin, topspin, or sidespin. That is 0° of gyro. If the skewer points straight at home plate, the ball spins like a football spiral. That is 90° of gyro. Most pitches land somewhere in between, and gyro degree tells you where.
Gyro degree matters because only the non-gyro part of the spin pushes the ball off its path. That useful part is called active spin, or transverse spin. Spin efficiency is roughly the cosine of the gyro angle, so the two numbers always move together. At 30° of gyro, about 87% of the spin is working. At 60°, only half is. Two pitchers with the same spin rate can get very different movement because their gyro is different.
Gyro is part of the design on some pitches. A gyro slider is built on it. With the axis pointed near the plate, the pitch gets little lift or sideways push, so it drops more than a fastball and moves only a few inches glove side. For four-seamers, curveballs, and sweepers, pitchers usually want less gyro so more of the spin turns into movement. The right number depends on the pitch and the shape you want.
Video explanation
Jake Fishman, PitchLab’s co-founder and CEO, pitched in the major leagues for the Miami Marlins. Here he explains gyro degree and what it means for your pitching.
What affects gyro degree
Grip and finger pressure
Where the fingers sit and which finger finishes the pitch changes the axis. A small shift in pressure can move gyro by several degrees.
Hand position at release
A hand that slips to the side of the ball tilts the axis toward the plate. Staying behind the ball keeps fastball gyro low.
Arm slot
Each arm slot makes some spin directions easier than others. Some slots add gyro to a fastball without the pitcher trying to.
Hand turn on breaking balls and changeups
Turning the hand over on a curveball or slider, or turning it out on a changeup, shifts the axis at release. How early and how far the hand turns changes the gyro reading.
Pitch intent
Gyro sliders and many cutters are thrown with the axis near the plate on purpose. Sweepers and curveballs are usually thrown with the hand more on top or to the side to cut gyro.
What’s a good gyro degree?
| Pitch type | Average | Good | Great | Excellent |
|---|---|---|---|---|
| Four-seam fastballLower is better | 25 | 20 | 15 | <10 |
| SinkerLower is better | 30 | 25 | 20 | <15 |
| Gyro slider | 75 | 78 | 81 | 84+ |
| SweeperLower is better | 60 | 55 | 50 | <45 |
| CurveballLower is better | 45 | 40 | 33 | <25 |
| ChangeupLower is better | 30 | 25 | 20 | <15 |
Lower is better for most pitches because less gyro means more of the spin moves the ball. Gyro sliders flip that rule since the pitch is built on bullet spin, and some sinkers and changeups carry extra gyro on purpose to get movement from the seams.
How PitchLab measures it
PitchLab reports gyro degree on every baseball pitch next to spin rate, active spin, and spin efficiency, so you can see how much of your spin is bullet spin. Session trends show whether grip or release changes are lowering your gyro over time.
Gyro degree FAQs
How do you measure gyro degree 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 reports gyro degree on every baseball pitch, next to spin rate, active spin, and spin efficiency.
Is there an app that measures gyro degree?
Yes. PitchLab measures gyro degree with just an iPhone and a tripod. PitchLab is free to start.
What’s the best app for lowering gyro on a fastball?
Look for an app that shows gyro degree on every pitch and tracks it across sessions, so you can tell whether grip or release changes are working. PitchLab does both with an iPhone.
What is a good gyro degree for a fastball?
For a four-seam fastball, under 20° is good and under 15° is great. That puts spin efficiency above about 94% and 97%. Lower gyro gives a four-seamer more ride. Sinkers can sit a little higher, around 20° to 30°.
What is the difference between gyro degree and spin efficiency?
They describe the same spin from opposite sides. Gyro degree is the angle of the spin axis toward the plate. Spin efficiency is the share of spin that creates movement. Efficiency is roughly the cosine of the gyro angle, so 0° of gyro is about 100% efficient and 90° is 0%.
What is a gyro slider?
A gyro slider is thrown with the spin axis pointed close to home plate, often at 75° of gyro or more. Little of the spin pushes the ball up or sideways, so it has almost no induced vertical break and only a few inches of glove-side movement. To a hitter it can look like a fastball before it drops.
How do you lower gyro degree on a fastball?
Start with the grip and hand position. Keep the fingers behind the ball through release, and check that pressure is even between the index and middle fingers. Small changes in wrist angle can move the axis several degrees, so test one change at a time and track the numbers.
