Speed testing
Sprint time calculator
Film the sprint, count frames from the athlete's first movement to the moment the torso crosses the finish line, and divide by the frame rate. A 40-yard dash run in 5.00 seconds averages 7.32 m/s (16.4 mph).
The rate the video was captured at, not the playback rate. iPhone slow motion is 120 or 240 fps.
From “Athlete's first movement” to “Torso crosses the finish line”. Use the end frame number minus the start frame number.
Elapsed time
5.00s
- Frames counted
- 1,200
- One frame lasts
- 4.2 ms
- Average speed over 40 yards
- 7.32 m/s
- In mph and km/h
- 16.4 mph · 26.3 km/h
How to time a sprint on video
- Place the camera level with the finish line and set it back far enough that the start is also in frame. A wide lens (0.5×) makes this possible for 40 yards.
- Record at 120 or 240 fps and keep the camera still.
- Step to the start frame: the athlete's first movement out of the stance.
- Step to the end frame: the first frame where the torso reaches the finish line.
- Enter the frame count, capture frame rate, and distance to get the time and average speed.
Formula
time = frames ÷ fps, average speed = distance ÷ time
Average speed covers the whole distance including the acceleration phase, so it is always lower than the athlete's top speed.
40 yards times in frames and average speed
| Time | Frames at 30 fps | Frames at 60 fps | Frames at 120 fps | Frames at 240 fps | Average speed |
|---|---|---|---|---|---|
| 4.40 s | 132 | 264 | 528 | 1,056 | 18.6 mph |
| 4.60 s | 138 | 276 | 552 | 1,104 | 17.8 mph |
| 4.80 s | 144 | 288 | 576 | 1,152 | 17.0 mph |
| 5.00 s | 150 | 300 | 600 | 1,200 | 16.4 mph |
| 5.20 s | 156 | 312 | 624 | 1,248 | 15.7 mph |
| 5.40 s | 162 | 324 | 648 | 1,296 | 15.2 mph |
| 5.60 s | 168 | 336 | 672 | 1,344 | 14.6 mph |
| 6.00 s | 180 | 360 | 720 | 1,440 | 13.6 mph |
Common mistakes
- Filming the finish from an angle. If the camera is not level with the finish line, parallax makes the athlete appear to cross early or late.
- Comparing video times with hand-held stopwatch times. Hand times usually read faster, often by around 0.2 seconds, because the timer reacts late at the start.
- Starting the count at a start signal on some runs and at first movement on others.
- Using 30 fps, which limits precision to about 33 ms per frame.
Frequently asked questions
Is timing a 40-yard dash from video accurate?
Timing from first movement to the finish at 120 or 240 fps is precise to within a few milliseconds per frame and removes the reaction delay of hand timing. It is not identical to electronic timing gates, so compare like with like.
Why are hand-timed 40s faster than electronic times?
The person with the stopwatch starts late, reacting to the athlete's movement, but stops close to on time because they anticipate the finish. The result is commonly around 0.2 seconds faster than electronic timing.
How do I calculate speed from a sprint time?
Divide the distance by the time. 40 yards is 36.58 meters, so a 5.00-second 40 averages 7.32 m/s, or about 16.4 mph.
Related terms
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KineVision plays video in slow motion, steps through it frame by frame, and includes a stopwatch, angle tools, and side-by-side comparison for coaching.
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