Free running calculators for every run, race and goal
Pace, race predictions, VDOT training paces, heart rate zones, treadmill conversions, pace bands and more — built on published sports-science models and explained in plain language.
Pace & Time
Race Prediction & Training
Heart Rate & Fitness
Treadmill & Track
Race Day
Pick your goal. Get the plan.
Every goal page includes exact km and mile splits, training paces, equivalent race times and example workouts.
Marathon
Half Marathon
10K
5K
Which running calculator do you need?
Most runners come here with one of four questions. Here is where to start for each:
“How fast did I run?”
Use the pace calculator for pace and splits, or the pace converter to switch between km, miles and speed.
“What could I race?”
The race time predictor turns one result into predictions for every distance from the mile to the marathon.
“How fast should I train?”
The VDOT calculator gives five training paces, and the heart rate zone calculator sets effort by heart rate.
“How do I pace race day?”
Build a plan with the marathon pace calculator and print it with the pace band generator.
Built on real sports science
Every prediction on this site uses a published, peer-reviewed or widely adopted model — never a black box. Race predictions use Peter Riegel’s endurance formula and the Daniels & Gilbert VDOT equations; heart rate zones use the Tanaka, Gulati and Karvonen methods; treadmill incline effects use Minetti’s energy-cost equation; and calorie estimates use the ACSM metabolic equations. Each calculator page explains the formula it uses, shows worked examples and lists its sources, so you can check the maths for yourself.
Designed for runners, not for sign-ups
No accounts, no email walls and no paywalls. Calculations run instantly in your browser, work in both metric and imperial units, and are designed to be as quick on a phone at the start line as on a laptop while you plan a training block.
Running calculator questions
Yes. Every calculator and pace chart on this site is completely free, with no sign-up, no account and no limit on how often you use them. All calculations run instantly in your browser.
Pace, speed, split and conversion calculations are exact arithmetic. Predictions — race times, training paces, heart rate zones and calories — use well-established published models such as the Riegel formula, the Daniels & Gilbert VDOT equations, the Tanaka and Karvonen heart rate methods and the ACSM metabolic equations. They are reliable estimates, but individual results always vary.
If you just want to know how fast you ran, start with the pace calculator. If you have a recent race result, the VDOT calculator gives you training paces for every type of run and the race time predictor shows what you could run at other distances.
Yes. Every calculator accepts and displays both metric and imperial units, and the pace converter switches between min/km, min/mile, km/h and mph instantly.