Jumping Jack Rep Counter
Stop counting in your head. Point your phone at yourself and every full-range jumping jack counts itself — sets, reps, and PRs logged automatically while you train your calves and shoulders, with core assisting. Free, in your browser, no account needed.
▶ Start Counting FreeHOW 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.
This is the same instruction sheet you’ll find on the ⓘ panel inside the app — with an animated demo next to it.
HANDS-FREE IN THREE STEPS
Prop your phone and get in frame
Set your phone at roughly torso height and stand facing the camera. The built-in camera test confirms your lighting, distance, and angle with live green checks before you start.
The AI locks a 17-point skeleton on you
GoodReps measures your shoulder angle (hip → shoulder → wrist) in real time, entirely on your device. No wearables, no clickers. No equipment at all — anywhere you can swing your arms.
Just work — the counter does the counting
A rep banks at the bottom (~165°) and re-arms when you return toward ~18°. Half reps don’t count, and after 3 clean reps it calibrates to your personal range of motion.
WHAT MAKES A REP COUNT
- 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.