Running Pace Calculator

Pace, speed, and splits

Enter a distance and the time you ran it, and this calculator gives your pace per kilometer and per mile, your average speed, and predicted finish times for every common race distance — from a single kilometer up to the full marathon.

How pace is calculated

Pace is simply time ÷ distance. A 50-minute 10K is 3,000 seconds over 10 km, or 5:00 per km (about 8:03 per mile). The split table multiplies that per-km pace out to each race distance, assuming you hold an even effort.

FAQ

Are the race predictions realistic?

They assume you can hold your current pace for the longer distance, which gets harder as the race grows. For a rough marathon prediction from a shorter race, expect to run a little slower than a straight extrapolation suggests — endurance, not just speed, sets your finish time.

What's the difference between pace and speed?

Pace is time per distance — minutes per kilometer or mile — and is how runners usually talk, while speed is distance per time, like kilometers per hour. They describe the same effort: a faster pace (a lower minutes-per-km number) means a higher speed.

How do I convert between min/km and min/mile?

Multiply your per-kilometer pace by about 1.609 to get your per-mile pace, since a mile is roughly 1.609 km. The calculator shows both at once, so you don't have to do the math yourself.

What pace do I need to break a target time?

Enter your goal distance with your target finish time and the tool gives the exact per-km and per-mile pace you'd need to hold. The even-effort splits then show what each checkpoint should read to stay on track.

Is this calculator free, mobile-friendly, and private?

Yes to all three — it's free with no sign-up, works in any phone browser so you can check splits at the track, and runs entirely on your device with nothing sent to a server.