About the Running Pace Calculator
A free, instant pace calculator. Solve pace, finish time, or distance from any two values — with a full split table and race time predictions for 5K, 10K, half marathon, and marathon.
What it is
The Running Pace Calculator solves the core running equation — distance = pace × time — from any two known values. Enter pace and distance to get your finish time, enter time and distance to get your pace, or enter pace and time to see how far you will cover. All calculations happen in your browser the moment you type, with no button needed and nothing sent to a server.
It also generates a full per-kilometre or per-mile split table showing your cumulative time at each distance marker, and predicts your finish time for the 5K, 10K, half marathon, and full marathon from your pace. You can switch freely between metric (min/km, km) and imperial (min/mi, miles) at any point — existing values convert automatically.
Key features
Solve any of the three values
Enter pace + distance to get time, time + distance to get pace, or pace + time to get distance. Leave whichever field you want computed blank and the tool fills it instantly.
Per-km / per-mile split table
When pace and distance are both known, a full split table appears showing the cumulative time at every kilometre or mile. Partial final splits (e.g. the 0.195 km at the end of a marathon) are included with their own time.
Race finish-time predictions
From any known pace, the tool instantly estimates your finish time for the 5K (5 km), 10K (10 km), half marathon (21.0975 km), and marathon (42.195 km). Useful for choosing a target pace before race day.
Metric and imperial
A unit toggle switches between km (min/km pace, distances in km) and mi (min/mi pace, distances in miles). Pace and distance values in the input fields convert automatically when you switch.
Distance presets
One-tap buttons for 5K, 10K, Half, and Marathon fill the distance field instantly. The preset labels stay the same in both unit modes; the underlying distance converts to km or miles as needed.
Fully private, no sign-up
Calculations run entirely in your browser. No data is stored, logged, or sent to any server. No account is required and there are no usage limits.
How the calculations work
Core formula
Total time (seconds) = pace (seconds per unit) × distance (units). All three values are linked by this identity: knowing any two gives the third directly.
Pace from time + distance
Pace (s/unit) = total time (s) ÷ distance. For example: 3000 s ÷ 10 km = 300 s/km = 5:00 min/km.
Time from pace + distance
Total time (s) = pace (s/unit) × distance. For example: 300 s/km × 42.195 km = 12658.5 s = 3:30:58.
Distance from pace + time
Distance = total time (s) ÷ pace (s/unit). For example: 3600 s ÷ 300 s/km = 12 km in one hour at 5:00 min/km.
Unit conversion
1 mile = 1.60934 km. Pace conversion: min/mi = min/km × 1.60934. Distance conversion: miles = km × 0.621371. All conversions are exact to 5+ significant figures.
Race predictions
Predicted time = pace (converted to s/km) × race distance (km). The pace is converted to per-km internally regardless of the selected unit, so all four standard race distances are accurate in both modes.
Pace vs speed
Pace and speed measure the same thing from opposite directions. Pace is time per distance — for example, 5:00 min/km tells you each kilometre takes five minutes. Speed is distance per time — for example, 12 km/h tells you how far you travel in one hour. Runners almost universally use pace because it translates directly to race planning: if your pace is 5:00 min/km and the race is 10 km, you know immediately that 50:00 is your target. Speed requires an extra step to reach the same conclusion.
To convert: speed (km/h) = 60 ÷ pace (min/km). At 5:00 min/km that is 60 ÷ 5 = 12 km/h. In miles: speed (mph) = 60 ÷ pace (min/mi).
A note on predictions and safety
This tool provides general information and is not medical advice. Exercise intensity should match your own fitness and health. Please consult a physician before starting a new exercise routine or training at high intensity—especially if you have any heart condition, injury, or health concern.
Race finish-time predictions assume perfectly even pacing with no elevation change, fatigue, or environmental variation. Real race performance differs from even-pace projections. Use predictions as a starting reference and refine them with your own training data and race experience.