How to film your vertical jump so the number is real

A badly shot video gives you the wrong number, and it's always wrong in the same direction: higher than reality. Video measurements are based on flight time, and nearly every filming mistake stretches that time out.

Here's how to record a jump that gives you a number you can trust, and the five mistakes that skew it.

How the measurement works, in one line

Once you're in the air you're a body in free fall, so the height you reach depends only on how long you stay off the ground: h = g × t² / 8. The software counts the frames between take-off and landing and converts them into centimetres.

Everything else follows from that: anything that artificially stretches your time in the air inflates the result.

The 5 mistakes that skew the result

1. Landing with bent knees

This is the most common mistake and the most expensive. If you land in a squat, your feet touch the ground later than they would on an extended landing: flight time goes up and the measurement goes up with it, even though you didn't jump a millimetre higher.

Rule: land with your legs roughly as extended as they were at the start, and absorb after contact, not before.

2. Taking off and landing in two different spots

If you jump forwards or backwards, part of the drive goes horizontal and the flight changes duration. Jump on the spot, and try to land where you took off.

3. Too few frames per second

At 30 fps each frame is worth around 33 milliseconds, and on a half-second flight a two-frame error matters. Shoot at 60 fps if your phone can do it, better still in slow motion at 120 or 240. Every recent iPhone and most Androids can: you set it in the camera settings, not inside the app.

4. Phone held in your hand

Camera movement makes the exact moment of take-off and landing uncertain. Rest the phone on something stable — a bag, a bench, the wall — or have someone hold it with their arms still.

5. Feet out of frame or in shadow

Take-off is read off your feet. Frame your whole body with a bit of margin underneath, film from the side and not from the front, and set yourself up so your feet stand out against the floor. If you play in a gym with light parquet and you're wearing light shoes, use the lighting to your advantage or change position.

The protocol, in practice

1. Phone resting on something, side on, hip height, whole body in frame
2. 60 fps or more
3. Warm up: a cold jump isn't your jump
4. Three attempts, with 30-60 seconds of rest between them
5. Land extended and on the spot
6. Keep the best of the three

Why consistency matters more than absolute accuracy

One detail almost nobody mentions: if what you care about is whether you're improving, you don't need a perfect measurement — you need a repeatable one. A systematic two-centimetre error, as long as it's always there, disappears in the difference between one test and the next.

That's why the real rule is: same shoes, same surface, same time of day, same type of jump, always rested. Change one of those variables between two tests and the comparison is useless.

Take the test

The JHP jump test is free: you upload the video (MP4 or MOV, 2-6 seconds), mark take-off and landing, and read the height in centimetres. The analysis runs inside the browser, so the video isn't uploaded to any server, and the page states the margin of error along with the result.

➡️ Upload your video and get your result

Then do it again in four weeks

One measurement on its own is useless data: you need the comparison. Four weeks is the right gap — long enough for a block to produce adaptations, short enough to notice quickly if the program isn't working.

The JHP subscription has 13 programs with day-by-day plans and a video for every exercise, at €99 a year:

• Jump Higher Program — 10 weeks of bodyweight jump work (€60)
• JHP Gym Edition — 16 weeks in the weight room (€60)
• Jumping Monster — 14 days of intensive plyometrics (€40)

You might also like: the six tests to assess your vertical jump and the explosive strength rating tables.