How do I convert min/km to min/mi?

Multiply your km pace by 1.609 to get the mile pace. So a 5:00/km pace becomes 5:00 × 1.609 = 8:02/mi. The math is the same in reverse — multiply min/mi by 0.621 to get min/km. This calculator does both automatically and also shows km/h and mph speed equivalents, which is what most treadmills and cycling computers display.

What's the difference between average pace and split pace?

Average pace is the total time divided by total distance — one number for the whole run. Split pace is the time for each kilometer (or mile) along the way. Even runners who maintain a consistent feel almost always have splits that drift by 10–30 seconds — early-race adrenaline makes the first km too fast, and fatigue slows the last few. Tracking splits is more honest about race-day pacing than the headline average.

Is this calculator only for runners?

No — the math (time, distance, speed) works for any pacing problem: cycling, swimming, kayaking, hiking, even driving. For cycling, switch the unit to km or mi and use min/km as a 'time per kilometer' input. For swimming, you can express splits per 100m by typing 0.1 km. The units don't know they're running shoes.

Why does negative splitting matter?

A 'negative split' means running the second half of a race faster than the first. Multiple decades of marathon-finishing data show that nearly every world record holder ran a negative or even split, and most personal bests for amateurs come from the same pattern. The mistake almost everyone makes is starting 10–20 seconds per km too fast because the first kilometer feels easy. Use this tool to figure out the average pace for your goal time, then deliberately run the first kilometer 5–10 seconds slower than that average.

How accurate is GPS-measured distance for pace?

GPS watches are typically within 1–2% on open road, but error grows in dense urban canyons (tall buildings reflect the signal) and on tight switchbacks (the watch undersamples the curve). For training, GPS pace is fine. For PRs and race comparisons, trust the certified course distance over your watch — at a marathon, a 1% GPS overshoot looks like a 5-second-per-km pace difference, which is huge.

Pace Calculator

Solve for running pace, finish time, or distance from any two known values. Works in km or miles with km/h and mph speed conversions and split times for 5K/10K/half/marathon.

What to solve for

Unit

Distance (km)

Total time

min

sec

Result

Pace per km

5:00 /km

Pace per mile

8:03 /mi

Speed (km/h)

12.00 km/h

Speed (mph)

7.46 mph

Pace × distance = time. Give us any two of those and we'll compute the third. Splits assume an even effort across the full distance — real races almost always drift, so use the result as a target, not a prediction.

How to Use

Solve for running pace, finish time, or distance from any two known values. Works in km or miles with km/h and mph speed conversions and split times for 5K/10K/half/marathon.

1Pick what you want to solve for — pace, finish time, or distance — using the mode selector at the top.
2Choose km or miles. The result panel shows both unit pairs and km/h + mph speed equivalents regardless.
3Enter the two known values. Use the 5K, 10K, Half, Marathon shortcuts under the distance field if you're racing a standard distance.
4Read the result. In 'finish time' mode you also get split times for every standard race distance shorter than your input — useful for goal-pace planning.
5Iterate. Bump pace by 5 seconds per km to see how much faster you'd finish, or swap to imperial to compare with a coach who only thinks in min/mi.

Key Features

Three modes — solve for pace, finish time, or distance — from any two of the three knowns
Automatic km/mi conversion plus km/h and mph display, so it works for cycling and treadmill use, not just running
Built-in race-distance shortcuts (5K, 10K, half marathon, marathon) and split times for every distance shorter than your target
Handles edge cases gracefully — leaves the result blank instead of showing NaN when fields are empty
Runs entirely in your browser — no tracking, no accounts, no API calls

Frequently Asked Questions

Learn More

Running Pace Math, Without the Headache — How to Plan a Race From the Calculator Up