Free tool
Serve speed: measure it with your phone
No radar needed. Film your serve from the side, upload the video: the tool tracks the ball frame by frame and works out its speed off the racket. Free, and your video never leaves your phone.
How to film it (30 seconds of setup)
- 1From the side, facing the server — outside the tramlines, 5-8 m away, the phone square to the direction of the serve.
- 2Phone fixed — on a tripod or wedged against the fence, in landscape. It must not move during the clip.
- 3In slow-motion — 240 fps if your phone can, otherwise 120. At normal speed (30 fps) the ball is too fast to measure.
- 4Everything in frame — the whole player, the toss up to its peak, and 3-4 m in front after the hit.
- 5One serve per video — trim the clip around a single serve: 2 to 5 seconds is enough.
How it works
Because the camera is still, the tool first learns what the empty court looks like, then picks out everything that moves. The ball is the only small object following a physically consistent path — that is how it is told apart from the racket, the arm or balls on the next court.
The key is scale. To turn pixels into metres, the tool uses your ball toss: a ball in the air always falls with the same acceleration, 9.81 m/s². Measuring the curve of the toss on screen tells us exactly how many pixels make a metre, right where you strike the ball. Nothing to measure, nothing to type in.
Phones sometimes export slow-motion as a stretched video. The tool spots it on its own by cross-checking gravity with the ball size (6.7 cm), then corrects the clock.
Finally, an air-drag model works back to the speed at impact: the same figure a radar gun shows.
How accurate is it?
- Filmed at 240 fps with the toss in view: a few percent of error, on par with an entry-level radar.
- At 120 fps: slightly less precise, but perfectly usable to track your progress.
- The limits: if the phone is at an angle to the serve, or the toss leaves the frame, the reading is less reliable. The tool always tells you, with a confidence level.
- It is an estimate, not a certified measurement: ideal for comparing yourself from one session to the next.
Serve speeds: ballpark figures
| Level | First serve |
|---|---|
| Beginner | 50-75 mph |
| Club player | 75-100 mph |
| Strong competitive player | 100-120 mph |
| Pros (men) | 120-145 mph |
| Pros (women) | 100-125 mph |
The fastest ever recorded: 163.7 mph by Sam Groth (2012) and 136.7 mph by Georgina García Pérez (2018). Amateur ranges are ballpark figures, not standards.
Frequently asked questions
›Can you really measure serve speed without a radar?
Yes. A video holds the two things you need: how far the ball moves between frames, and the exact time between frames. In slow-motion there are enough frames right after the hit to compute the speed precisely.
›What frame rate do I need?
Slow-motion: 240 frames per second ideally, 120 at minimum. At normal speed (30 fps) the ball only stays in frame for 2 or 3 images — too few.
›Is my video uploaded to a server?
No. The whole analysis runs in your browser, on your phone or computer. The video is never sent or stored.
›Why does my result differ from a radar?
A radar that isn't pointed straight reads low, and our measurement has its own margin (shown under the result). A few mph apart is normal; beyond that, check the phone was square to the serve.
›Does it work for forehands or padel?
The tool is tuned for the tennis serve, because the ball toss acts as the ruler. On a forehand it works with lower confidence (the ball size is used as the scale instead).
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