Fitness & running calculators
7 free tools
Quick estimates for training and race planning — predict a finish time, dial in your pace and splits, or check your VO2 max — all running right in your browser. These are training aids, not medical advice.
Estimate the watts behind a cycling speed from rider and bike weight and gradient.
Turn a recent race into a predicted finish time for another distance using Riegel's formula.
Enter a goal distance and time to get your target pace and a full split-by-split table.
Convert a step count into miles and km from stride or height, with a rough calorie estimate.
Enter a swim distance and time to get pace per 100m or 100yd, plus a per-50 split.
Convert treadmill mph to min/mile and min/km, with a rough note on what incline costs you.
Estimate VO2 max from a 1.5-mile run time or the Cooper 12-minute distance.
Frequently asked questions
How accurate are these calculators?
They're solid estimates, not guarantees. Formulas like Riegel's race predictor and the VO2 max field tests are well-established, but weather, hills, sleep, and how you've actually trained all move the real number. Use them to set targets and track trends.
Do I need to sign up or install anything?
Nope — everything runs entirely in your browser. There's no login, no app to download, and none of your numbers get uploaded anywhere.
Is this medical advice?
It isn't. These are training and performance estimates for healthy athletes. If you have a health condition or you're starting something new and intense, check with a doctor first.