Smash speed calculator

This badminton smash speed calculator works out speed the only way a phone can: distance divided by time. Pick how far the shuttle flew, enter how many video frames it took and the frame rate you filmed at, and you get the average speed over the flight. Because a shuttle slows down brutally fast, the calculator also estimates the speed it left your racket at, which is the number every published smash speed refers to.

How to measure smash speed with your phone

1. Film in slow motion. 120 or 240 fps. At 30 fps one frame is a full 33 ms, which on a flight of a third of a second is a 10% error before you have done anything wrong. At 240 fps a frame is 4 ms.
2. Film side-on if you can. A camera level with the court, a few metres back from a sideline, sees the whole flight and makes the contact and landing frames easy to spot. Our filming guide covers mounts and angles.
3. Find two frames. Step through the clip in an editor that shows frame numbers. Note the frame where racket meets shuttle and the frame where the shuttle touches the floor (or crosses a line you know the position of).
4. Measure the distance. Use the presets, which come from the official court dimensions (see badminton court dimensions), or tape-measure from where you hit to where it landed. Leave "add the drop" on if your end frame is the landing: the path from a 2.5 m contact point to the floor is a few percent longer than the floor distance.
5. Repeat. Do five smashes and take the best and the median. One number is an anecdote.

The full walkthrough, with the three main methods compared, is in how to measure your badminton smash speed.

Why your average speed looks so low

Most people who try a badminton smash speed test are disappointed: the calculator says 90 km/h when they expected 250. The maths is fine. A shuttlecock weighs about 5 grams and has a skirt that acts like a parachute, so drag hammers it. At smash speeds the drag force is hundreds of times its weight, and the speed decays exponentially with distance: v(r) = v₀ · e^(−r/L).

L is the shuttle's "aerodynamic length", about 4.5 m for a feather shuttle according to physicists who filmed elite smashes at 3,000 frames per second (Collet, 2026, building on Cohen, Darbois Texier, Quéré & Clanet's 2015 The physics of badminton). In plain terms: the shuttle loses half its speed roughly every 3 m. A smash that leaves the racket at 300 km/h is down to about 40 km/h by the time it lands 9 m away, and its average over that flight is under 100 km/h.

Integrating that equation gives the flight time, t = (L / v₀)(e^(d/L) − 1). Solve it for v₀ and you get the speed off the racket from the distance and time you measured. That is what the lime "speed off the racket" figure shows.

How accurate is a frame-count smash speed measurement?

The calculator shows a range from a ±1 frame timing error, because you can never be sure the true contact happened exactly on a frame. The range shrinks with more frames: 46 frames at 120 fps is about ±2%, while the same smash at 30 fps is only about 11 frames and roughly ±9%. The distance is the other big error source; the estimate of the speed off the racket is also only as good as the drag model.

The tap timer is there for when you cannot step through frames. Be honest about it: simple visual reaction time is around a fifth of a second, and while anticipating a hit makes your taps better than that, they are still easily tens of milliseconds off, on a flight that only lasts a few hundred milliseconds. Tapping along to 4× or 8× slow-motion playback divides that error by 4 or 8, which is why we offer it. Tap several times; the spread of your attempts is your real error bar.

What is a good badminton smash speed?

Published smash speeds are all initial speeds, measured right off the racket. In a 1998 study using 120 Hz video, elite Taiwanese players smashed at 55–70 m/s (about 200–250 km/h) and collegiate players at 50–58 m/s (180–209 km/h). High-speed footage of today's international players shows smashes leaving the racket at around 380–400 km/h. The records, per Guinness World Records, are 565 km/h for men and 438 km/h for women (both set in a test at Yonex's factory in 2023), and 426 km/h in competition (Mads Pieler Kolding, 2017). More context in average smash speed by level and the fastest smashes ever recorded. To add speed, start with how to smash harder.