No account or file needed. Enter distance and time to calculate your pace, predict race finishes, compare paces side by side, and plan your splits.
How the basic functions work
Calculate pace. Enter distance (km or miles) and time (HH:MM:SS). The calculator returns your pace in min/km, your speed in km/h, and a fitness-level read of your time. You can also work backwards: enter a target pace and see the finish time for common race distances.
Race-time prediction. Project from your current time using either a linear hold (same pace maintained) or the Riegel formula, which accounts for the fact that longer distances are harder per kilometer. Table covers 5K, 10K, half marathon and marathon.
Pace comparison table. See at a glance which pace produces which finish time — from 4:00 min/km to 7:00 min/km, with finish times for 5K, 10K, half and full marathon side by side.
Plan your splits. For your chosen distance the calculator builds a splits table with the target time per kilometer or mile. Useful for race day and tempo workouts.
Pace vs. speed. Pace (min/km) measures how long you take per kilometer — what runners use. Speed (km/h) measures how far you cover in an hour — what cyclists and treadmills use. Conversion: km/h = 60 ÷ pace. A 5:00 min/km pace equals 12 km/h.
Pace calculator
Enter distance and time — pace is calculated automatically.
| Pace /km | 5 km | 10 km | 15 km | Half | Marathon |
|---|
Amber row = your current pace. Green badges mark milestone times.
Enter any race distance and a target time — equal splits appear automatically.
Pick a distance and target time to see your splits.
Run log, progress chart and group comparison — demo data is loaded below; add your runs to make it yours.
About the extended functions
The extended section turns the calculator into a full running log. Same rules as the basic side: no account, no cloud, no tracking. Data stays on your device, optionally exported as a CSV file you own.
Log your runs. Distance, time, date, notes — per run. Personal records for 5K, 10K, half marathon, marathon and any custom distance you set are detected and marked automatically.
Progress chart. Pace and distance over weeks or months, with switchable views. Helps you see whether your training is actually producing fitness gains, without you having to interpret raw numbers.
Group mode. Running club, family run, team event — compare multiple runners on the same distance. Time, pace, steps and notes per person, with a chart and a ranking. CSV import and export, so the group result lives wherever you need it.
CSV import & export. Bring in existing data from Strava, Garmin Connect or your own spreadsheet via CSV. Templates are linked from the gateway. Your data stays portable — even if you stop using this calculator one day.
Delete the run/walk data saved in this browser? Your loaded data stays visible until you reload or clear.
Browsers can clear this when you delete cookies or run low on storage. It won't transfer to other devices. Always use Download your file as your primary backup.
| # | Run | Time | Pace | Steps | Date |
|---|---|---|---|---|---|
| Upload your file or log a run to see records. | |||||
Already have data? Load it before adding new runs.