Push-ups
Your phone counts your push-ups. And it says which ones it did not count.
Push-ups are the most measured exercise of the product: six real recordings replayed through the actual model, at five frame rates, with the gap published. Everything on this page comes from that bench.
Where to put the phone
On the floor, to your side, about a metre away.
The camera needs to see your shoulder, elbow, wrist, hip, knee and ankle. From the side, a body on the floor shows all six. Facing you, the ankles hide behind the body, and that is exactly what the count needs to judge the line of your back.
The phone in place
Someone in push-up position, the phone on the floor to their side, about a metre away. An ordinary room, not a gym.
1200 × 900
The app checks the framing before the clock starts and says what is missing in plain words: step back, your feet are not visible. It declares you ready on its own, because nobody gets up to press a button while in push-up position.
What closes a rep
Down, then back up, and held.
Top of the cycle
Arms straight, body in line. The position has to be held briefly: a body that never really extends never closes a cycle either.
Bottom of the cycle
The elbow has to pass its threshold. A movement that stops halfway is seen, and not counted: it is not a refusal, it is a rep that has not happened yet.
The return is held
A return held for less than eighty milliseconds does not close the rep. That guard is what stops a shake, or a tracking glitch, from being counted as a push-up.
What the bench gave
Within two reps, and we publish the gap.
Six recordings, replayed through the real model with no rule applied, then compared to a count read by eye on the signal. At the frame rates the app actually uses, the gap stays within two reps. At four frames per second it degrades, and that degradation is known rather than hidden.
A count without a margin is a claim, not a measurement. Any app can say it counts your push-ups; the question is what it does with the ones it did not see.