Speed GunHow to Measure Pitch Speed with Your Phone Camera
Measuring pitch speed used to mean buying a radar gun that cost hundreds of dollars. Today your phone camera can do a surprisingly accurate job. The idea is simple: distance the ball traveled ÷ time it took. A camera captures dozens to hundreds of images per second, so if you count which frame the ball leaves on and which frame it arrives on, you know how long the flight took.
What you need
- A phone (ideally one that can shoot high-speed video at 120fps or more)
- A tripod or stand to hold the phone steady
- The distance between the thrower and the catcher (on a regulation mound, 18.44m from the rubber to home plate)
Camera position makes or breaks accuracy
The best spot is off to the side of the ball's flight path. The ball needs to cross the frame so you can clearly pinpoint where it starts and where it ends. If you film from behind the catcher or the pitcher, the ball barely moves across the screen and the error gets much bigger.
- Stand far enough back that the entire pitching distance fits in the frame.
- Always keep the phone fixed. Handheld footage shakes, and you'll misread where the ball is.
- The brighter the scene, the faster the shutter, so the ball blurs less.
Where do you start and stop the clock?
The usual approach is to mark the moment the ball leaves the hand (release) and the moment it hits the catcher's mitt. The catch is the distance. Pitchers stride at least a step forward off the rubber before letting go, so the ball actually travels less than 18.44m. For an adult pitcher it's roughly 16.5–17m. Plug in 18.44m as-is and your reading comes out 5–10% faster than the real speed.
Error by fps (frames per second)
In 30fps video, there's about 0.033 seconds between frames. A ball traveling at 120 km/h (about 75 mph) covers roughly 1.1m in that time. Being off by just one frame at the start or end throws the result way off. Shoot at 240fps and the gap between frames shrinks to about 0.004 seconds, cutting the error to roughly one-eighth.
| Recording fps | Time between frames | Distance a 120 km/h ball travels |
|---|---|---|
| 30 | ~0.033 s | ~1.1m |
| 60 | ~0.017 s | ~0.56m |
| 120 | ~0.008 s | ~0.28m |
| 240 | ~0.004 s | ~0.14m |
Quick recap
- Mount the phone off to the side and record at the highest fps you can.
- Find the release frame and the frame where the ball hits the mitt.
- Enter the actual distance between those two points.
- Measure 3–5 pitches the same way and look at the average so one mistake doesn't skew things.
Under good filming conditions, phone measurements can land within a few percent of a radar gun. That only holds if your distance and frame selection are accurate, though, so following the tips above matters most.