FIT file analyzer, computed locally
Run/walk splits and calorie estimates from any .fit file.
Select a file from your watch or bike computer. It is decoded, smoothed, and integrated here in the browser — the file never leaves this device.
No file loaded.
Breakdown
| Split | Distance | Time | Pace |
|---|---|---|---|
| Run | — | — | — |
| Walk | — | — | — |
| Estimate | Value | Basis |
|---|---|---|
| Calories | — | — |
Run segments
Plain-text report
Ask about this session
Answers are computed from the loaded file's numbers, locally. No network requests.
Method
Speed is smoothed with a 10-second rolling window to remove GPS jitter. Points at or above 2.22 m/s count as running; everything else counts as walking. Energy cost is integrated second by second with the ACSM equations (running: 0.2 · speed + 0.9 · speed · grade + 3.5; walking: 0.1 · speed + 1.8 · speed · grade + 3.5).
If the file contains per-point altitude, each second uses its own measured grade. If not, a flat grade is used: a whole-route net grade would misstate the cost of climbs and descents, so it is shown only as a labeled reference figure, never as the primary estimate.
This is a direct port of analyze_fit.py; outputs were verified identical on real recordings.