The app uses the flight time of your jump and the displacement equation from physics to calculate the height of your jump. Refer to the image below:

The equation above does not take into account air resistance which would affect acceleration however the effects should be negligible.

However, the biggest thing that would affect your jump height using the app would be when the timing of your takeoff and landing. To get the most accurate result you want to mark your takeoff right when your foot leaves the ground and landing right when your foot touches the ground.

Ideally, you would want to land as minimal knee bend. Since bending your legs on landing would artificially increase flight time and therefore inflate jump height.

If there are any bugs / problems with the website. Please send us an email at vertcheck@gmail.com with an explanation of the issue is. We will try to fix it as soon as possible.