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Running Pace Calculator

Solve for running pace, finish time or distance in miles or kilometers, with per-mile and per-km splits, negative-split planning and Riegel race-time predictions.

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Distance

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Hours

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Seconds

Pace minutes

Pace seconds

Pace and splits per

Negative split

Riegel fatigue exponent

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How it works

pace = time ÷ distance · time = pace × distance · distance = time ÷ pace · speed = distance ÷ time · Riegel: T₂ = T₁ × (D₂ ÷ D₁)^1.06

Pick what you want to solve for. With a distance and a finish time the calculator gives your pace; with a distance and a pace it gives the finish time; with a time and a pace it gives the distance you will cover. Pace is shown per mile and per kilometer (1 mile = 1.609344 km), along with speed in mph, km/h and m/s and the time for one 400 m track lap. The splits table lists every mile or kilometer with the time for that split and the running total. By default the splits are even. Enter a negative-split percentage under More options and the second half is run that much faster than the first while the finish time stays the same, which is how most coaches plan a race. The race predictions use Pete Riegel’s 1977 formula, T₂ = T₁ × (D₂ ÷ D₁)^1.06. The exponent is just above 1 because pace slows as races get longer. You can raise it to 1.07–1.08 if your endurance base is modest.

Worked example

A 28:30 5K is 1,710 seconds over 3.107 miles (5 km). That is 1,710 ÷ 3.107 = 550.4 s, or 9:10 per mile, and 1,710 ÷ 5 = 342 s, or 5:42 per km. The average speed is 10.5 km/h (6.54 mph). Riegel’s formula predicts 1,710 × (42.195 ÷ 5)^1.06 = 16,401 s, about 4:33:21, for a marathon. To find a 10K finish time at 5:00 per km, choose Finish time and enter 5 min 0 s per kilometer: 300 s × 10 = 3,000 s, or 50:00.

Sources: Riegel PS. Athletic records and human endurance. American Scientist, 1981 · NIST — length conversion (1 mile = 1.609344 km)

Frequently asked questions

How do I work out my pace?

Divide your finish time by the distance. Convert the time to seconds first, divide, then turn the answer back into minutes and seconds. For example, 50 minutes for 10 km is 3,000 ÷ 10 = 300 s, which is 5:00 per km or 8:03 per mile.

What’s a good 5K time?

Finishing at all beats not starting. Casual adult runners commonly land between 25 and 40 minutes. A sub-25 5K is a solid recreational benchmark, and sub-20 is competitive club level.

How accurate are the race predictions?

Riegel’s formula works best between about 3.5 minutes and 4 hours and when you have trained for the target distance. It tends to be optimistic for the marathon, especially for a first marathon or a runner with low weekly mileage. Treat the prediction as a best case, not a promise.

What is a negative split?

Running the second half of a race faster than the first. Enter, say, 2% under More options and the calculator slows the first-half pace and speeds up the second-half pace so the total time is unchanged. Even or slightly negative splits produce the best times for most runners, because going out too fast costs more later than it gains early.