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Heart Rate Zones
See time in each heart rate zone and the training load (TRIMP) of a workout from FIT, TCX or GPX.
Free, no uploads, no sign-up. Runs 100% in your browser.
How Heart Rate Zones works
Activity and health files are read in your browser. Nothing is uploaded, and no account is needed. Zones use percent of max heart rate or heart rate reserve (Karvonen). Training load uses the Banister TRIMP formula. Pauses longer than 30 seconds count as 30.
Input: FIT, TCX, GPX. Output: CSV.
How to use Heart Rate Zones
- Drop a workout file with heart rate.
- Enter your age or max heart rate, and resting heart rate.
- Pick % of max or heart rate reserve.
- Read the zones and load, and download CSV.
Tips
- Most watches can export FIT files from their app or website.
- Health files reveal a lot about you. Here they never leave your device.
- These tools give training information, not medical advice.
Heart Rate Zones FAQ
- Are my files uploaded?
- No. This tool runs entirely in your browser tab. Files are read from your disk into memory and the result is generated locally.
- Is it free? Are there limits or watermarks?
- Free and open source (MIT). There are no file-size caps, daily quotas, accounts or watermarks.
- Does it work offline?
- Yes, once the page (and any engine it needs) has loaded, it keeps working without a connection thanks to the service worker cache.
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