Jumping jack counter
Count jumping jacks with your camera. The app checks that your hands go above your head and your feet go wider than your shoulders before it counts. Runs in your browser; nothing is uploaded.
Set up the camera (facing the camera)
- Stand facing the camera 2.5–3 m away so your hands above your head and your feet are both in view.
- Portrait orientation works well; make sure the ceiling or a lamp is not right behind you, as strong back-light hides your arms.
- Clear space around you — arms and feet both move out to the side.
How the counter decides what counts
One jumping jack is “open” then “closed”. Open means both wrists are above your nose and your ankles are more than 1.3× your shoulder width apart. Closed means both wrists are below your shoulders and your ankles are less than 1.0× your shoulder width apart. A rep is counted each time you return to closed.
These are our counting rules for the app, not an official standard. Angles come from Google MediaPipe pose landmarks and can be off by several degrees with loose clothing or poor light.
Form points
- Land softly on the balls of your feet with slightly bent knees.
- Bring your arms all the way overhead; half-raised arms are not counted as open.
- Keep a steady rhythm rather than going as fast as possible.
Common problems
- Arms only to shoulder height: raise them above your head.
- Feet staying narrow: jump them out wider than your shoulders.
- Partly out of frame: step back until hands and feet are visible.
Exercise at your own risk and stop if you feel pain or dizziness. This app counts movements; it is not medical or physiotherapy advice.