Pick what to solve for - pace, finish time or distance - and fill in the other two; the result updates as you type. The form starts pre-filled with a 5K in 25:00 so a real answer (5:00 min/km) is visible immediately. Overwrite the distance or pick a race preset from 5K to marathon, switch between kilometers and miles (entered values convert in place), and read the pace both ways, the speed in km/h and mph, and an even-pace split table for the standard checkpoints below the result.
Pace Calculator
The pace calculator solves the runner's triangle: enter any two of distance, time and pace and it gives you the third, entirely in your browser. Ask it what pace finishes a 10K in 50 minutes, what a marathon takes at 6:00 min/km, or how far you covered in 40 minutes at your usual pace - the answer updates as you type.
Pace always shows both ways - min/km and min/mile - together with the speed in km/h and mph, so a treadmill setting, a race plan and a GPS watch reading can be compared without converting anything by hand. A race-preset list fills in the exact 5K, 10K, half-marathon (21.0975 km) and marathon (42.195 km) distances, and switching between kilometers and miles converts the numbers you already entered in place instead of resetting the form.
Below the result an even-pace split table projects cumulative times at the standard checkpoints - 1 km, 1 mile, 5K, 10K, 15K, half marathon, 30K and the full marathon - at the computed pace. The projections assume a perfectly even pace: real race splits vary with terrain, weather and fatigue, so treat the table as a planning estimate, not a coaching plan. Nothing you type is stored or sent anywhere, and no account is needed.
For other everyday math on this site, the percentage calculator handles generic percent questions rather than pacing, the fuel cost calculator does trip math in money rather than minutes, and the TDEE calorie calculator estimates the day's energy burn that training sits inside.
Frequently Asked Questions
What does the pace calculator do?
It solves the runner's triangle: pick which of distance, time or pace to compute, enter the other two, and the result updates as you type - with the pace shown in both min/km and min/mile, the speed in km/h and mph, and an even-pace split table at the standard race checkpoints.
How do I convert a min/km pace to min/mile?
You do not have to - every result shows the pace both ways. A mile is 1.609344 km, so a 5:00 min/km pace reads 8:03 min/mile, and switching the unit select converts the numbers you already entered in place instead of clearing them.
What pace do I need to finish a marathon in 4 hours?
Pick the marathon preset (42.195 km), enter 4:00:00 and solve for pace: 5:41 min/km, which is 9:09 min/mile. The split table below the result then shows the even-pace passing times at 5K, 10K, half and 30K for that plan.
Are the split times exact race predictions?
No. The table projects a perfectly even pace, and real race splits vary with terrain, weather and fatigue. Use it as a planning estimate - a pacing target per checkpoint - not as a coaching plan or a guarantee.
Does anything I enter leave my browser?
No. The math runs locally in the page - nothing is uploaded, stored or sent, no account is needed, and the tool does not read a GPS watch or training app; every number is one you type in.