belt.fit is a phone strap belt you wear on your body — paired with an app that uses your phone's sensors to track KPIs for any activity that moves you. No special hardware. Just strap, move, and know.
Strap · Sense · Move · Know
Your phone rides the strap. The accelerometer reads every movement. These gauges update live — power, speed, balance, and reps, all from the sensors already in your pocket.
The strap puts your phone on your body. The accelerometer does the rest. Works for any exercise where the phone moves with you.
The belt.fit strap holds your phone on your body. The app turns every movement into data. That's it.
Order the belt.fit strap — a slim, secure phone holder you wear on your hip, waist, arm, or chest. Your phone slots right in.
Launch Belt, pick your activity, and set your goal — reps, duration, power target, or intensity. The app configures itself for your movement type.
Your phone's accelerometer and gyroscope sense every rep, strike, and rotation through the strap. No wires, no special sensors — just you moving.
Live and post-session: rep count, power output, speed, balance, intensity, and fatigue — for any activity that moves your body.
Six axes of motion. Processed on-device. Zero data sent anywhere.
Belt reads accelerometer and gyroscope at 100Hz — detecting the exact moment, direction, and force of every rep or strike as it happens.
Rep targets, duration goals, power thresholds, rest periods. Belt tracks every metric against your goal and alerts you live.
No buttons, no taps. Belt counts every rep from your motion signature. Squat, punch, row, step — all detected automatically.
Every movement classified by intensity band. Know when you're peaking, coasting, or fading — and when to push harder.
Detects which side of your body is overworking — per round, per session.
Tracks speed and power decay across your session. Pinpoints exactly when performance drops.
Calendar view, trend charts, and milestone tracking across every session you've done.
belt.fit sells the phone strap. Wear it on your hip, waist, arm, or chest — your phone stays locked in while you move freely.
Every byte of movement data lives on your iPhone. Nothing leaves your device. No sign-up required to start.
Pair with Apple Watch for simultaneous wrist + hip sensing — dual-axis data for the full body picture.
Push your limits. Know your numbers.