How is running pace calculated?

Pace is simply your total time divided by the distance, expressed as minutes and seconds per unit. If you run 10 km in 50 minutes, that's 50 ÷ 10 = 5 minutes per kilometre, shown as 5:00 /km. The calculator does the division for you and formats the result as M:SS for both kilometres and miles, so you never have to convert decimal minutes into seconds by hand.

What's the difference between pace and speed?

They describe the same effort from opposite directions. Pace is time per distance (minutes per km or mile) and gets smaller as you get faster. Speed is distance per time (km/h or mph) and gets bigger as you get faster. Runners usually think in pace because it maps directly onto splits, while cyclists and treadmills often show speed — so the calculator gives you both at once.

How do I convert pace per km to pace per mile?

One mile is about 1.609 kilometres, so a mile takes longer to cover at the same effort and its pace number is larger. Rather than multiplying in your head, just enter your run once: the calculator shows pace per km and pace per mile side by side using the exact 1.609344 conversion factor, so the two always agree.

Can I use this to plan a race pace?

Yes. Tap a race preset (5K, 10K, Half or Marathon) to load the exact distance, then type the finish time you're aiming for to see the pace you'd need to hold. Or enter a distance and a pace-equivalent time from a recent run to estimate a realistic target. Remember that longer races are usually run slightly slower per km than short ones, so don't assume your 5K pace holds for a marathon.

Calculators

Running Pace Calculator

Turn a distance and a time into your running pace per kilometre and per mile, plus speed in km/h and mph — with 5K, 10K, half and marathon presets.

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Distance

Race preset

Time

Hours : minutes : seconds — leave blanks at 0.

Pace per kilometre

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Enter a distance and a time

Per km

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Per mile

—

Speed km/h

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Speed mph

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What a running pace calculator does

A pace calculator turns two numbers — how far you ran and how long it took — into the figures runners actually train by: pace per kilometre, pace per mile, and speed in km/h and mph. It replaces fiddly mental arithmetic (dividing a time in hours-minutes-seconds by an awkward distance) with an instant, always-consistent answer.

Everything runs in your browser and updates live as you type.

How pace and speed are worked out

There are two quick steps:

Pace. Total time in seconds divided by the distance gives seconds per unit, which the calculator formats as minutes:seconds. Run 5 km in 25:00 and that's 1500 s ÷ 5 = 300 s = 5:00 /km.
Speed. Distance divided by time in hours gives km/h (or mph). That same 5 km in 25 minutes is 5 ÷ 0.4167 h ≈ 12.0 km/h.

Because kilometres and miles are linked by the fixed factor of 1.609344, the per-km and per-mile figures are always in exact agreement.

How to use it

Enter your distance and pick the unit — km or mi.
Or tap a race preset: 5K, 10K, Half (21.0975 km) or Marathon (42.195 km) to fill the distance instantly.
Enter your time in the hours, minutes and seconds fields (leave any blank field at zero).
Read your pace per km, pace per mile, km/h and mph. Use Copy for a one-line summary or Clear to reset.

A worked example

You run a 10K in 52:30. That's 3150 seconds over 10 km:

Pace per km: 3150 ÷ 10 = 315 s = 5:15 /km
Pace per mile: 10 km = 6.2137 miles, so 3150 ÷ 6.2137 ≈ 507 s = 8:27 /mi
Speed: 10 km ÷ 0.875 h ≈ 11.43 km/h (about 7.10 mph)

Aiming for a sub-50 10K next time? You'd need to hold 5:00 /km — a 15-second-per-km improvement.

A note on accuracy

The maths is exact for the numbers you enter, but real runs aren't run at a perfectly even pace — hills, wind and fatigue all move your splits around, so treat a single average pace as a summary rather than a promise for every kilometre. GPS watches also introduce small distance errors on twisty or tree-covered routes.

For converting other distances and units, the Unit Converter is handy, and if you're tracking training alongside energy needs the TDEE Calculator complements it well. You can find everything on the all tools page.

Private by design

No account, no upload, no tracking of your runs — the calculation happens locally in your browser with plain JavaScript, so your distances and times never leave your device.

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