Free running calculators
Plan your race pace, find your Zone 2 heart rate, and estimate your VO2 max with science-based calculators built by a running coach.
Race pace calculator
Enter a race distance and goal time to get your required pace per mile and per kilometer, plus cumulative mile splits from the 5K to 100 miles.
Plan your race pace →Zone 2 heart rate calculator
Find your aerobic base-building heart rate range using the MAF formula, percent of max HR, or the Karvonen heart rate reserve method.
Find your Zone 2 range →VO2 max calculator
Estimate your VO2 max with five validated field tests: resting heart rate, Rockport walk, Queens College step test, Cooper run, and 2000m row.
Estimate your VO2 max →Tools that answer the three questions every runner asks
Almost every training question comes down to one of three things: how fast should I run, how easy should my easy days be, and how fit am I right now. These calculators answer each one with formulas taken straight from the exercise science literature, not guesswork.
The race pace calculator converts any goal time into the pace you need to hold, with cumulative splits for every mile of the race. The Zone 2 heart rate calculator gives you the ceiling for your easy runs using four established methods, so your aerobic base actually gets built instead of eroded by junk miles. The VO2 max calculator estimates your aerobic engine with five field tests you can do without a lab.
Everything runs in your browser. Nothing you type is sent to a server, stored, or tracked. The formulas behind each tool are documented on the calculator pages, so you can check the math yourself.