Calculator
Choose a mode, enter your values, then press Calculate. The result appears above this form.
Example data
Sample entries and outputs to help you sanity-check your inputs.
| Distance | Time | Speed (km/h) | Pace (min/km) |
|---|---|---|---|
| 5 km | 25:00 | 12.00 | 5:00 |
| 10 km | 55:00 | 10.91 | 5:30 |
| 1 mile | 8:30 | 11.36 | 5:17 |
Formula used
- Speed:
v = d / twheredis distance andtis time. - Time:
t = d / vwhen you set a target speed. - Distance:
d = v × twhen you set a speed and duration. - Pace per km:
pace = 1000 / v(seconds per kilometer), then formatted as mm:ss. - Unit conversions: 1 km = 1000 m, 1 mile = 1609.344 m, km/h = m/s × 3.6.
How to use this calculator
- Select a calculation mode (speed, time, or distance).
- Enter the required values for that mode, including units.
- Optionally add body weight for a rough calorie estimate.
- Press Calculate to see results above the form.
- Use the split table to plan training or race targets.
- Export your results using the CSV or PDF buttons.
Speed, pace, and unit alignment
Running speed expresses how far you travel per time. This tool calculates m/s, km/h, and mph together, then converts the same effort into pace per kilometer and per mile. For example, 12.00 km/h equals 3.333 m/s and about 7.46 mph, producing a 5:00 per km pace. A steady 8:00 per mile pace equals 7.5 mph and 12.07 km/h for treadmill checks.
Distance and time quality checks
Reliable inputs matter more than complex math. A 5 km entry should be 5000 m internally, while 1 mile becomes 1609.344 m. The calculator rejects zero or negative distance and time. If you type 0:25:00, the model uses 1500 seconds for consistent conversions and export-ready results. Rounding is displayed for clarity, while calculations keep full precision to prevent drift across conversions and splits.
Scenario planning with target speed
Use “time” mode to set a goal speed and predict finish time. At 10.00 km/h, 10 km is projected at 60:00. Increase the target to 12.00 km/h and the same 10 km becomes 50:00. Small changes compound, especially in longer events, so exploring multiple targets is useful. For interval work, set speed and time, then use “distance” mode to estimate repeat length.
Training splits as actionable checkpoints
Splits turn a single number into a plan. With constant speed, split time scales linearly: time = distance ÷ speed. At 5:00 per km pace, 400 m is 2:00 and 1 mile is about 8:03. Compare actual lap times to these checkpoints to identify pacing drift.
Energy estimate for health tracking
The calorie estimate uses a common running rule: roughly 1 kcal per kilogram per kilometer. A 70 kg runner covering 5.0 km is about 350 kcal. This is an approximation, not a medical measurement, but it helps contextualize weekly training load and recovery needs.
Exporting for consistent progress reviews
After each calculation, download CSV for logs or PDF for sharing. Store date, distance, time, and pace so trends are visible. If your 5 km pace improves from 6:00 to 5:30 per km, that is a 30-second gain per km, or 2:30 faster over 5 km. Review monthly averages and note conditions; heat, hills, and fatigue can explain deviations without changing fitness level much.
FAQs
What units can I enter for distance and speed?
Distance accepts meters, kilometers, or miles. Speed accepts m/s, km/h, or mph. Results always show all unit conversions together for easy comparison.
Why does pace display as minutes and seconds?
Pace is time per fixed distance, so mm:ss is easier to interpret than decimals. The calculator converts speed into seconds per kilometer and per mile, then formats it cleanly.
Can I use treadmill settings with this calculator?
Yes. Set your treadmill speed in km/h or mph, choose “time” mode, and enter your planned distance. You can also predict distance covered during a timed session.
How accurate is the calorie estimate?
It uses a simple rule of thumb based on body weight and distance. Terrain, efficiency, and conditions change real energy cost, so treat the value as a planning estimate.
How should I enter long run times?
Use hours, minutes, and seconds. For example, 1 hour 30 minutes is 1:30:00. The calculator converts the full time into seconds internally for consistent outputs.
Why might my watch splits differ from these splits?
These splits assume constant speed. GPS drift, turns, stops, hills, and pacing variation change real split times. Use the table as a target, then compare to actual laps.