Tools
Free browser tools for cardio training. No signup, no install; the numbers and the timers, ready to use.
Calculators
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VO2 Max Calculator
Estimate your VO2 max from any of 5 validated tests: Cooper run, 1.5-mile run, Rockport walk, beep test, or resting heart rate. With your age and sex category, plus a projection of how fast you can raise it.
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Max Heart Rate Calculator
Your max heart rate by age from four published formulas, your five training zones in bpm, and Karvonen zones from your resting heart rate.
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Zone 2 Heart Rate Calculator
Your easy aerobic range at 60-70% of max heart rate, from your age or measured max, with Karvonen zones and a zone 2 by age table.
Interval Timer
Interval Timer
Build any work/rest sequence with named intervals, rounds, countdown, and audio cues. Shareable via URL, runs in the browser.
Preset Timers
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Tabata Timer
Run the original 4 minute Tabata protocol in your browser. Pre-loaded and ready to start.
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30 Second Interval Timer
30 seconds work, 15 seconds rest, 10 rounds. Pre-loaded and ready to start.
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1 Minute Interval Timer
60 seconds work, 30 seconds rest, 10 rounds. Pre-loaded and ready to start.
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HIIT Timer
45 seconds work, 15 seconds rest, 8 rounds. Pre-loaded for high intensity sessions.