BeastieGuides · What counts as a rep
Why Rep Counters Disagree (and Which Number to Trust)
A watch, a nose-tap app, a phone camera and a friend can give four different counts for one set. Each measures something different. Here is what each one sees.
Rep counters disagree because they aren't measuring the same thing. A wrist wearable feels one arm move, a nose-tap or proximity app notices your face getting close to the phone, a camera with pose detection checks your joint angles, and a friend counts whatever they were watching. Give all four the same set of push-ups and you can get four numbers, each of them "right" by its own definition of a rep.
The useful question isn't which counter is accurate. It's which definition of a rep each one is using, and whether that definition can tell a full rep from a half one.
Four ways to count a rep
| Method | What it actually detects | Where it tends to miscount |
|---|---|---|
| A friend counting | Whatever they're looking at | Gets generous when tired, watches the head instead of the elbows, loses count |
| Wrist wearable | Motion of one arm | Push-ups, where the hands stay planted; other arm motion may look like a rep |
| Nose-tap, proximity or face-distance app | Your face reaching, or nearing, the phone | Can't see the hips, so a sagging rep that reaches the phone looks like a good one |
| Camera pose detection | Joint positions and angles across the whole body | Needs your whole body in frame and enough light; refuses reps it can't see clearly |
None of these is a trick. They are four honest measurements of four different things.
The friend counting
A person is the original rep counter, and a good judge is hard to beat. The problems are consistency and attention. A friend counting your set is also tired, also distracted, and usually on your side. They tend to watch your face, and it is easy to dip the head towards the floor while the arms barely bend. By rep 40, very few people are still checking lockout.
If you are counting for someone, watch from the side at elbow height, count on the lockout, and treat doubt as a no. The push-up competition rules are written for exactly that job.
Wrist wearables
A wrist counter reads motion sensors on one arm and works backwards to a rep. Research systems have shown this can work well for many exercises: RecoFit, a Microsoft Research project presented at CHI 2014, used an arm-worn inertial sensor to find, recognise and count repetitive exercises.
Push-ups are an awkward case for any wrist method, for a physical reason: your hands stay planted on the floor. The wrist tilts as you go down and up, but it doesn't travel the way your chest does. A shallow dip and a full rep produce similar signals at the wrist, so a wrist counter has less to go on in a push-up than in, say, a curl. And because it only feels one arm, it has no view of your hips at all.
So if you've searched "watch push-up count wrong", that is usually the reason. It isn't a fault in one product; it's the limit of measuring a whole-body movement from one wrist.
Nose-tap, proximity and face-distance apps
A whole family of push-up apps counts by putting the phone under your face. Their own App Store listings describe the methods:
- Tapping with your nose. Push Ups Counter - Trainer tells you to put the phone in front of your face and "Tap the screen via nose for counter."
- The proximity sensor. Push Up Counter - 100 Pushups says it "Counts completed push-ups by the proximity sensor or your nose", and its version notes mention adding AR face tracking.
- Front-camera face distance. PushFit says its front camera tracks your face and "measures your distance from the phone."
All three measure one thing: how close your face got to the phone. That is a reasonable proxy for depth, and it is cheap and simple. What it can't see is the rest of you. If your hips sag towards the floor, your face still reaches the phone, and the rep counts. If you drop your head rather than bending your elbows, your face can get there early. And the top of the rep, the lockout, is not something a face-distance check can confirm.
Camera pose detection
The fourth method uses a camera that can see your whole body. A pose model finds key points (shoulders, elbows, hips, knees, ankles) on every frame, and the app checks the angles between them. This is how Beastie works, and it is described in detail on how Beastie counts.
Because it sees the joints, a pose counter can ask the question the other methods can't: did the rep actually finish? Beastie's push-up rule is that the elbow passes below about 90 degrees and returns above about 160 degrees, with the shoulder-hip-ankle line staying within about 15 degrees. Squats and jumping jacks have their own rules.
The trade-off is that a camera needs to see you. The phone has to be propped up with your whole body in frame, in reasonable light. When the model loses track of a limb partway through a rep, a strict counter has to choose between guessing and refusing. Beastie refuses: if it isn't sure, it doesn't count. That makes it strict by design, and it means its misses lean towards your count being lower, not higher. These are Beastie's game rules for scoring a rep, not a sports-science standard.
Why the numbers drift apart
Even with a perfect sensor, counters disagree because each has to decide what a rep is. Three choices do most of the damage.
- Depth. Some count a rep when the face or chest gets close to something. Others need a joint angle. A shallow rep can pass one and fail the other.
- Lockout. A counter that only checks the bottom will happily count bounces. One that needs the arms straight at the top won't.
- Debounce. Every counter has to ignore wobbles near a threshold. Too loose and a single rep counts twice; too tight and a fast rep is missed. Beastie uses tolerance bands and a minimum rep duration so a bounce that turns around early is not a rep.
So when a nose-tap app says 35 and a pose counter says 28, the likeliest story isn't that one of them is broken. It's that seven reps reached the phone but missed depth, lockout or the hip line.
How to get a number you can compare
- Use the same counter every time. Your progress is only visible if the definition of a rep doesn't change between sets.
- Use the same counter as the person you're comparing with. Two friends on two different methods aren't racing the same race.
- Prefer a counter that can see the joints that define the rep. For a push-up that's the elbows and the hip line; for a squat, the knees; for a jumping jack, the ankles and the wrists.
- Distrust a count that feels generous. A counter that lets the marginal rep through makes every number on the board worth less.
Counting with Beastie
Beastie counts push-ups, squats and jumping jacks with the phone camera. A live skeleton is drawn over you, white where the movement is clean and orange where form broke, and a refused rep comes with an instruction like "chest lower!" rather than a "failed". The counting runs on the phone; video is never uploaded or stored, and it works with no signal.
It runs on iPhone and Android. Your first counted set is free, whether that is a solo set or a duel you start, and answering a friend's challenge is always free. After that, Beastie Pro unlocks everything, starting with a 7-day free trial. Get Beastie and see what your set looks like when only the finished reps count.
Beastie is general fitness information, not medical advice. Check with a professional before starting a new exercise routine, and stop if you feel pain.
Questions people ask
Why is my rep counter not accurate?
Usually because it measures something other than the rep. A wrist sensor feels one arm's motion, a nose-tap or proximity app detects your face near the phone, and a friend watches whatever they happen to be looking at. None of those is the same as checking that the movement went all the way down and all the way back up.
Why is my watch's push-up count wrong?
A wrist counter infers reps from the motion of one arm. In a push-up your hands stay planted on the floor, so the wrist moves much less than your chest does, and a shallow dip and a full rep can look alike. That is a limit of measuring at the wrist, whichever watch or app you use.
How do rep counter apps work?
There are four common methods: motion sensors in a wearable, a tap or proximity check when your face reaches the phone, front-camera face tracking that measures how close your face gets, and pose detection, where a camera finds your joints and checks angles. Each one defines a rep differently, which is why they disagree.
Which rep count should I trust?
The one whose definition of a rep you agree with, applied the same way to every rep. If a counter can't see your elbows or knees, it can't tell a full rep from a partial one.
How does Beastie count reps?
With the phone camera. A pose model running on the phone finds your shoulders, elbows, hips, knees and ankles, and a rep only banks when the joint angles cross Beastie's thresholds with clean form. Video is never uploaded or stored.
Send a rep battle. Let the camera judge.
Beastie counts push-ups, squats and jumping jacks on your phone — only clean reps count — and your friend can answer from a link, no app needed to see it.
Get Beastie