Tools
Calculators
Free calculators for runners: estimate your fitness, plan your pace, set your heart rate zones and work out your splits – all free, no sign-up.
VO2max calculator
Estimated VO2max/VDOT, equivalent race times and training paces from a single race result.
Pace calculator
Work out pace, time and distance, convert min/km ↔ km/h, and adjust pace for heat.
Heart rate zones
Maximum heart rate and 5 training zones with the Karvonen method, from age and resting HR.
Splits calculator
Per-kilometre splits from a goal time, the halfway split and even or negative-split strategy.
Calories calculator
Calories burned running from your body weight and distance – with gross and net values.
Age grading
Age- and sex-adjusted performance percentage and time, from the WMA tables.
Calculators for smarter training and racing
Running works best when you build it on numbers: knowing what pace to run, what heart rate to train at, and what you are realistically capable of on race day. These tools turn a few basic inputs into instant answers – right in your browser, with no data sent anywhere.
The calculations are based on established sports-science formulas (Jack Daniels' VDOT system, the Daniels–Gilbert formula, the Karvonen method, the ACSM equations and the WMA age-grading tables). The results are indicative estimates; combine them with your own experience and, where needed, professional advice.