What spin efficiency means
Spin efficiency compares useful spin to total spin. It's the share of the rotation that runs across the ball's path and moves it through the Magnus effect. The rest is gyro spin, which turns the ball around its direction of travel like a football spiral. Spin efficiency and gyro degree describe the same axis in two ways. A pitch with a 0-degree gyro angle is 100 percent efficient. At 30 degrees it's about 87 percent, and at 60 degrees it's 50 percent.
High efficiency is the goal for most fastballs. A four-seam fastball with 95 percent efficiency and a 12:30 to 1:00 spin axis gets close to the most ride its spin rate allows. That's the "rising" fastball hitters swing under. Curveballs also tend to play better with higher efficiency, since more active topspin means more depth. Changeups and sinkers often run high too, with the axis tilted toward the arm side for fade.
Low efficiency can be the plan. A gyro slider is thrown with mostly bullet spin on purpose. With little lift from its spin, it falls well below where a fastball would be. Cutters also mix in gyro spin. The right number depends on the pitch and the shape you want, so read efficiency next to spin axis. Together they show where the movement goes and how much of it you get.
Video explanation
Jake Fishman, PitchLab’s co-founder and CEO, pitched in the major leagues for the Miami Marlins. Here he explains spin efficiency and what it means for your pitching.
What affects spin efficiency
Fingers behind the ball
A release with the fingers directly behind the ball makes clean backspin. Fingers that drift to the side, even slightly, add gyro spin.
Arm slot
Arm slot changes how easily a pitcher gets behind the ball. Some slots make an efficient fastball easy and an efficient curveball harder, and others work the opposite way.
Forearm rotation at release
Pitchers who naturally turn the hand outward (supinate) or inward (pronate) get different efficiency on different pitches. Working with that tendency is usually easier than fighting it.
Grip and seam orientation
Where the fingers sit on the ball tilts the spin axis. A small shift in grip can change efficiency noticeably.
Pitch intent
A fastball, a curveball, and a gyro slider each want different efficiency. The target comes from the pitch shape you're trying to build.
Fatigue and timing
When a pitcher tires or rushes, the hand often gets to the side of the ball. Efficiency can drift down late in a session.
What’s a good spin efficiency?
| Pitch type | Average | Good | Great | Excellent |
|---|---|---|---|---|
| Four-seam fastball | 90 | 94 | 97 | 98+ |
| Sinker / two-seamDepends on pitch shape | 87 | 90 | 93 | 96+ |
| ChangeupDepends on pitch shape | 92 | 94 | 96 | 98+ |
| Curveball | 70 | 77 | 84 | 90+ |
| Sweeper | 50 | 57 | 64 | 71+ |
| Gyro sliderLower is better | 25 | 20 | 15 | ≤10 |
MLB-level estimates. Rows marked "depends" show typical to high values, and the right target depends on the shape the pitcher wants. Gyro sliders are built on bullet spin, so lower efficiency is the goal. High school and college pitchers often land in similar ranges, since efficiency comes more from release than from strength.
How PitchLab measures it
PitchLab shows spin efficiency as a percentage on every pitch, alongside active spin, gyro degree, and spin axis. Set an iPhone on a tripod about 2 ft behind the pitcher and compare efficiency pitch by pitch as you adjust a grip.
Spin efficiency FAQs
How do you measure spin efficiency 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 shows spin efficiency as a percentage on every pitch, next to active spin, spin axis, and gyro degree.
Is there an app that measures spin efficiency?
Yes. PitchLab measures spin efficiency with just an iPhone on a tripod. PitchLab is free to start.
What’s the best app for improving spin efficiency?
The best tool for spin efficiency shows it on every pitch, right after you throw, so you can compare grips and seam orientations side by side. PitchLab does this with an iPhone and keeps every session so you can see the trend.
What is a good spin efficiency?
It depends on the pitch. For a four-seam fastball, 90 percent is about average in MLB and 95 percent or more is very good. Curveballs usually land between 60 and 80 percent. Gyro sliders are meant to be low, often 25 percent or less.
Is higher spin efficiency always better?
No. Higher efficiency helps pitches that rely on ride or depth, like four-seam fastballs and curveballs. Gyro sliders and many cutters work because a big share of their spin is gyro. Choose the efficiency that fits the shape you want the pitch to have.
What spin efficiency should a slider have?
A gyro slider usually sits around 25 percent or lower, which gives it tight, short break and little lift. A sweeper needs more active spin to move sideways, often 50 to 65 percent or higher. MLB sliders as a group average in the high 30s.
How do you improve spin efficiency?
Start with release. For fastballs, work on keeping the fingers directly behind the ball as it leaves the hand. Small grip and seam changes can also shift the axis. Change one thing at a time and track the result, so you know what moved the number.
