Pace vs speed - what's the difference?

Same physics, inverted convention. Speed is distance per time (e.g. 10 km/h); pace is time per distance (e.g. 6:00 / km). Runners talk in pace because it makes split times trivial - to run a marathon in 4 hours you need a pace of 5:41 / km, and 5:41 is the same number you'll see on the watch every kilometre.

Does it account for elevation?

No. Pace calculations are flat-ground only. Real-world pace on a hilly course can be 30 seconds per km slower than the flat equivalent; experienced runners adjust on the fly.

Pace Calculator

Running pace, distance and time - any two, get the third. Splits in km and miles.

Runs in your browser

Fill any two of the three fields - pace, distance, time - and we'll compute the third. Pace is shown in both min/km and min/mi. Splits for 5K, 10K, half marathon and marathon at the chosen pace are listed below.

Distance unit

Solve for

Distance (km)

Time (HH:MM:SS)

Pace (min:sec / unit)

Distance

10.00 km

Time

00:50:00

Pace / km

5:00 / km

Pace / mi

8:03 / mi

Splits at this pace

5K00:25:00
10K00:50:00
Half01:45:29
Marathon03:30:59

How to use it

Pick what to solve for
Pace, time, or distance - the field with the spinner becomes the output.
Fill the other two
Pace as min:sec / km, time as HH:MM:SS, distance in km or mi (toggle units).
Read splits
Per-kilometre and per-mile splits for 5K, 10K, half, marathon are shown below.

What is it?

A pace calculator solves the three-variable triangle of distance, time and pace. With any two known, the third is one division away. The interesting parts are formatting (min:sec / km is the runner's standard, not decimal minutes), units (km / mi side-by-side because most races still publish in mi internally), and the per-distance split tables.

When to use it

Planning a race day: 'I want to break four hours on the marathon - what pace do I need?'. Working backwards from a training run: '8 km in 41:36, what was my pace?'. Comparing two efforts on different distances: 'is today's 5K at 4:20 / km faster or slower than last week's 10K at 4:40 / km?'.

Common mistakes

Confusing decimal minutes (1.5 min) with min:sec (1:30 min); the calculator accepts both formats but it's easy to typo. Targeting a pace that's faster than your race pace by accident - 4:00 / km looks similar to 4:30 / km but the time difference at marathon distance is huge (2:48 vs 3:09). And forgetting that 'easy pace' for endurance runs is 60-90 seconds per km slower than race pace.

FAQ

Pace vs speed - what's the difference?: Same physics, inverted convention. Speed is distance per time (e.g. 10 km/h); pace is time per distance (e.g. 6:00 / km). Runners talk in pace because it makes split times trivial - to run a marathon in 4 hours you need a pace of 5:41 / km, and 5:41 is the same number you'll see on the watch every kilometre.
Does it account for elevation?: No. Pace calculations are flat-ground only. Real-world pace on a hilly course can be 30 seconds per km slower than the flat equivalent; experienced runners adjust on the fly.

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