A worked example
12 km/h = 5:00/km = about 7.456 mph. A 400 m lap takes exactly 2:00.
Speed converter
Convert km/h or mph to running pace and calculate a constant-speed 400-metre lap time.
YOUR LITTLE WORKBENCH
Speed converter
Start with the example, then make it your own. Results update as you type.
How this is calculated
Seconds per km = 3,600 ÷ km/h. A 400 m lap takes seconds per km × 0.4.
YOUR PLAN / LIVE RESULT
Running pace
5:00 /km- Pace per mile
- 8:03 /mi
- Speed
- 12 km/h
- Speed
- 7.4565 mph
- 400 m lap
- 2:00
All conversions assume a constant average speed. The 400 m result is for an actual 400 m distance; outer track lanes have different distances unless the start positions are staggered.
THE METHOD / 01
Know what goesinto your result.
Seconds per km = 3,600 ÷ km/h. A 400 m lap takes seconds per km × 0.4.
Keep the assumptions clear
All conversions assume a constant average speed. The 400 m result is for an actual 400 m distance; outer track lanes have different distances unless the start positions are staggered.
A FEW USEFUL ANSWERS
Good to know.
Are my inputs uploaded?
No. Calculations run locally in your browser. The host still receives normal requests for website pages and assets.
Can I keep my result?
Export a CSV, or use Print / PDF and choose Save as PDF in your browser. Inputs are not saved between visits.
Do I need an account?
No sign-up, paid API or subscription is required. Both language versions use the same calculation logic.
STRIDEKIND / TOOLKIT
A little help for every step.
01
Pace calculator
Enter distance and elapsed time to calculate pace per kilometre, pace per mile and average speed.
Open tool02
Finish time
Estimate elapsed time from a constant pace and distance. Includes 5K, 10K, half-marathon and marathon presets.
Open tool03
Race splits
Create an even-pace split card for a target finish time, including the final partial kilometre or mile.
Open tool