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.
Fueling Calculator
Hourly carbohydrate, fluid and sodium needs for running, based on recognized sports science guidelines.
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.