FormFit AIHow the AI works
FormFit AI uses AI in three separate ways. Each one runs on your own device. This page explains what each does, what information it uses, and where it can get things wrong.
In one line. A pose model finds your joints, tuned rules count your reps and score your form, and an on-device language model writes a short note from your totals. None of it needs the internet, and none of it uploads your video.
1. Seeing you: pose tracking
For every camera frame, a machine-learning model estimates where your body's joints are, such as shoulders, elbows, hips, knees and ankles. On iPhone and iPad this is Apple's Vision framework (about 19 body points). On Android it is Google's MediaPipe Pose Landmarker (33 points).
- It runs on your phone's own processor, live, while you train.
- Each frame is analysed and discarded. We don't record video.
- To power the skeleton replay in your history, the app keeps a few skeleton snapshots per rep (coordinates, not images) on your device only. They are not synced to the cloud.
2. Counting reps and scoring form: tuned rules
Once the joints are known, FormFit AI works out angles (for example your knee and hip angle in a squat) and follows them through the stages of a repetition: start, down, bottom, up. This part is rule-based, not a chatbot:
- Each exercise has target angle ranges and timing limits that we chose and tested.
- A rep counts as clean when you reach the needed depth or range and don't rush it. A rep that is too fast or too shallow is still logged but marked.
- The form score (0 to 100) reflects how closely your angles matched the target for that rep.
We use rules here because they are predictable, explainable and work with no connection. The thresholds are guidance, not a judgement of your technique by a trained coach.
3. The AI form coach: an on-device language model
After a workout, FormFit AI first shows a few plain observations worked out on your phone, such as "form slipped from 85 to 65 by the end" or "4 reps were rushed". If you tap Get my AI coaching, a language model built into your phone turns those numbers into a short, personal note.
| What the model is given | What it is not given |
|---|---|
| Per exercise: sets, reps, clean reps, average form score, form in the first and last third of reps, average seconds per rep and how much it varied, count of rushed and too-shallow reps, and your recent average for that exercise. Workout length and calories. | Video, photos, pose points, your name, email, account or location, and the names of any custom exercises you created. |
- Where it runs: Apple Intelligence on supported iPhones and iPads (iOS 26 or later); Gemini Nano through Google's ML Kit on supported Android phones. The text is generated on the device.
- Nothing is uploaded to us or to any AI provider, and your data is not used to train any model.
- Availability: on devices that don't support on-device AI, the AI coach section is simply not shown. The core app, with rep counting and form scores, works the same on every device.
- The first time on some Android phones, Google downloads the model once.
What the AI can and can't do
- It can spot patterns in your numbers, like fatigue late in a set, a rushed pace, or shallow depth, and turn them into plain advice.
- It can't see your body, diagnose pain or injury, or know your health. It doesn't know what weight you used or how you feel.
- It can be wrong or generic. Treat it as a prompt to think about your training, not as a coach, doctor or physiotherapist. If something hurts, stop and see a professional.
Accuracy and limits
- Rep counts and form scores depend on lighting, steady phone placement, your whole body being in view, and clothing that contrasts with the background. Loose clothing or a tilted phone can throw the joints off.
- Body measurements from the optional scan are estimates from two photos analysed on your device, not clinical measurements.
- Calories are estimated from exercise type, time and your weight, and are shown as a range.
Your control
- The AI coach only generates a note when you tap Get my AI coaching.
- You can use FormFit AI without an account and without ever using the AI coach.
- Delete everything from Profile ▸ Settings ▸ Delete account & all data. See Delete your data and the privacy policy.
Questions about how the AI works? Email support@compsgeek.in.