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.
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.