Jumping Jack Form Check
Wondering if your jumping jack is solid? Prop up your phone — GOODREPS watches your shoulder angle (hip → shoulder → wrist) live and scores every rep while you train your calves and shoulders, with core assisting. Free in your browser today; coming to Google Play and the App Store.
Coming to Google Play & the App Store▶ Try The Form Check
LIVEHOW TO DO A PROPER JUMPING JACK
Setup Stand facing the camera, feet together, arms at your sides.
- Jump your feet wide while raising your arms fully overhead.
- Jump back to the start.
- Keep a steady bouncing rhythm.
Same sheet as the ⓘ panel in the app — animated demo included.
THREE STEPS TO A SCORED JUMPING JACK
Prop your phone and get in frame
Phone at roughly torso height, stand facing the camera. A quick camera test checks lighting, distance, and angle before you start.
The camera locks a 17-point skeleton on you
GOODREPS measures your shoulder angle (hip → shoulder → wrist) on-device — no wearables. No equipment at all — anywhere you can swing your arms.
Move — and watch the form bar
The bar fills from ~18° toward ~165° at the bottom. Cut range short and it tells you; full ROM is what counts.
WHAT THE CAMERA WATCHES
- Your arm sweep, live — from roughly 18° at your sides up toward 165° overhead. T-shaped half-jacks don't bank; full overhead claps do.
- Your personal range of motion — after 3 clean reps the counter calibrates to you, so it stays honest at speed.
- The top of every rep — stop at shoulder height and the form cue chimes in: "Arms fully overhead."
COMMON JUMPING JACK MISTAKES
Arms stopping at shoulder height
The half-jack. Swing all the way up — hands meeting (or nearly meeting) overhead is what makes the rep count.
Feet barely leaving the floor
A shuffle isn't a jump. Get both feet wide and back together with a real hop — light, springy, on the balls of your feet.
Landing stiff-legged
Straight-knee landings send the impact to your shins and knees. Land soft with a slight bend, like the floor is quietly loud.
Slouching as you tire
Posture is the first thing fatigue steals. Stay tall — ribs up, eyes forward — to the last rep.
PRIVATE BY DESIGN
Pose detection runs in your browser via TensorFlow.js. Camera frames are analyzed in real time and immediately discarded — nothing is recorded, nothing leaves your phone, and we never see them. Sign-in is optional; skip it and everything stays local.
QUESTIONS, ANSWERED
Do I need any equipment for jumping jacks?
None at all — just a bit of space and your phone propped up facing you. Softer flooring or shoes help if you're jumping a lot.
Does it work in a home gym or low light?
Run the built-in camera test first — it checks your lighting, distance, and angle with live green checks before you start. If a rep still slips through, manual counting is always one tap away.
Is my camera feed uploaded anywhere?
No. Pose detection runs entirely on your phone, in your browser. Frames are analyzed in real time and immediately discarded — nothing is recorded, nothing is uploaded.
RELATED GUIDES
Free forever — camera counting for all 60 exercises, no account needed. Pro (voice coaching, programs, depth-camera form checks) is $7/mo, $49/yr, or $99 once. No ads, ever.