What spin axis means
Spin axis tells you which way a pitch's spin is pushing it. Picture a clock on the ball as you look from behind the pitcher toward home plate. The hand points in the direction the spin moves the ball. At 12:00 the ball has pure backspin and gets the most lift. At 6:00 it has pure topspin and drops faster. At 3:00 or 9:00 it has sidespin and moves sideways. Times in between blend the two.
Strictly speaking, the axis is the line the ball spins around, and the clock hand sits at a right angle to it. Most pitch trackers, PitchLab included, use "spin axis" for the clock reading, and some call it spin direction or tilt. For a right-handed pitcher, arm side is toward 3:00 and glove side is toward 9:00. A lefty is the mirror image, so a righty's 1:00 fastball matches a lefty's 11:00.
Spin axis works together with spin efficiency. The clock gives the direction of the push, and efficiency tells you how much of the spin is doing the pushing. A slider at 9:00 with 30 percent efficiency moves far less than one at 9:00 with 70 percent. Seams can also nudge a pitch off the path its spin axis predicts. Check the movement numbers alongside the clock to see how the pitch really moved.
Video explanation
Jake Fishman, PitchLab’s co-founder and CEO, pitched in the major leagues for the Miami Marlins. Here he explains spin axis and what it means for your pitching.
What affects spin axis
Arm slot
A higher arm slot tilts spin toward 12:00, and a lower slot tilts it toward 2:00 or 3:00 for a right-hander. Arm slot is one of the biggest drivers of a pitcher's natural fastball axis.
Finger position at release
Fingers directly behind the ball push the clock toward 12:00. Fingers on the side of the ball push it toward 3:00 or 9:00.
Forearm rotation
Turning the hand inward (pronation) tilts spin toward the arm side, as on a sinker or changeup. Turning it outward (supination) tilts it toward the glove side, as on a curveball or slider.
Grip
Each grip puts the fingers in a certain spot at release. A two-seam or changeup grip usually tilts the axis toward the arm side compared with a four-seamer.
Pitch intent
The same pitcher needs different clocks for different pitches. The goal is a fastball axis that fits the arm slot and off-speed pitches whose axes move away from it.
Seam effects
The seams can push a pitch in a direction the spin alone wouldn't. This is why the spin-based clock and the actual movement don't always match.
What’s a good spin axis?
| Pitch type | Average | Good | Great | Excellent |
|---|---|---|---|---|
| Four-seam fastball (ride)Depends on pitch shape | 1:15 | 1:00 | 12:45 | 12:30 |
| Sinker / two-seamDepends on pitch shape | 1:45 | 2:00 | 2:15 | 2:30 |
| ChangeupDepends on pitch shape | 2:00 | 2:15 | 2:30 | 2:45 |
| CutterDepends on pitch shape | 11:30 | 11:15 | 11:00 | 10:45 |
| CurveballDepends on pitch shape | 7:30 | 7:15 | 7:00 | 6:45 |
Clock readings for a right-handed pitcher, seen from behind the mound. Each tier shows the tilt that gives more of the pitch's signature shape, such as ride, run, cut, or depth. The best tilt depends on arm slot and on how the pitch pairs with the fastball. For a lefty, mirror the clock, so 1:00 becomes 11:00.
How PitchLab measures it
PitchLab reads each pitch from an iPhone on a tripod about 2 ft behind the pitcher, the same view the spin clock uses. It shows spin axis as a clock face on every pitch, next to spin efficiency and gyro degree.
Spin axis FAQs
How do you measure spin axis 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 axis as a clock face on every pitch, from the same view the spin clock uses.
Is there an app that measures spin axis?
Yes. PitchLab measures spin axis with just an iPhone, and shows it next to spin efficiency and gyro degree on every pitch. PitchLab is free to start.
What’s the best app for working on spin axis?
Use an app that shows spin axis and movement together on every throw, so you can see how a change in axis changes the pitch’s shape. PitchLab shows both on every pitch, with the video.
What is a good spin axis for a fastball?
For a right-handed pitcher, a four-seam fastball meant to ride works best close to 12:00, usually between 12:30 and 1:15. A sinker or two-seamer wants more tilt, around 1:45 to 2:30, for extra run and sink. The best axis also depends on arm slot, since a low slot won't produce a 12:30 fastball easily. Lefties mirror these times.
What does 1:00 mean in spin axis?
A 1:00 reading means the spin pushes the ball mostly up and a little toward the 3:00 side, as seen from behind the pitcher. For a right-hander, that's backspin tilted slightly toward the arm side. It's one of the most common four-seam fastball readings for righties. For a lefty, the same shape reads 11:00.
What is the difference between spin axis and spin direction?
The spin axis is the imaginary line the ball rotates around. Spin direction, or tilt, is where that spin pushes the ball, shown as a clock time. The two sit at right angles to each other. Most pitch trackers, including PitchLab, show the clock reading and call it spin axis.
Why doesn't my pitch move the way the spin axis says?
Spin axis only predicts the push from spin. Seam orientation can create extra movement that spin alone doesn't explain, and a large share of gyro spin weakens the push. That's why trackers also report movement in inches. When the clock and the movement disagree, the seams are often the reason.
