Crunch Form Check
Is your crunch actually good? Prop your phone up and find out — GoodReps watches your hip angle (shoulder → hip → knee) live and scores every rep as you train your core. Free, in your browser, processed entirely on your device.
▶ Check My Form FreeHOW TO DO A PROPER CRUNCH
Setup Lie on your back, side-on to the camera, knees bent, hands by your head.
- Curl your shoulders up off the floor toward your knees.
- Squeeze your abs at the top.
- Lower with control — don't yank your neck.
This is the same instruction sheet you’ll find on the ⓘ panel inside the app — with an animated demo next to it.
THREE STEPS TO A SCORED CRUNCH
Prop your phone and get in frame
Set your phone at roughly torso height and set up side-on to 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 hip angle (shoulder → hip → knee) in real time, entirely on your device. No wearables, no sensors. No equipment — floor space and your phone propped side-on.
Move — and watch the form bar
The bar fills as you travel from ~160° toward ~120° at the bottom. Stop short and it tells you; a rep only counts through the full range of motion.
WHAT THE CAMERA WATCHES
- Your torso angle, live — from roughly 160° lying flat up toward 120° at the crunch. Neck-bobs don't bank; real trunk flexion does.
- Your personal range of motion — after 3 clean reps the counter calibrates to how you move.
- Whether the crunch actually happens — pulse too small and the form cue insists: "Crunch fully."
COMMON CRUNCH MISTAKES
Pulling on your neck
Hands yanking your head forward strain your neck and skip your abs. Fingertips behind your ears at most — the crunch starts at your ribs.
Sitting all the way up
A crunch lifts your shoulder blades, not your whole back. Coming fully upright shifts the work to your hip flexors.
Dropping back down
The lowering half is half the exercise. Come down slow enough that your abs — not gravity — control the descent.
Holding your breath
Exhale as you crunch up; it lets your abs contract fully. Inhale on the way down and keep a rhythm.
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 to count crunches?
No — just floor space (a mat is more comfortable) and your phone propped side-on so the camera can see your torso fold.
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.