Pace Calculator

How to use the pace calculator

Enter the distance you covered and the time it took, and the tool gives you three ways of describing the same effort: pace per kilometre, pace per mile, and speed. The distance starts at 5, with a km/mi toggle so you can work in whichever unit your watch or your race is measured in, and the time is split into hours, minutes, and seconds — defaulting to 25 minutes flat. Leave the example in place to see the tool work, then swap in your own numbers.

Set the distance first and pick the unit that matches how you recorded it. A track session or a metric race goes in as kilometres; a US road race or a treadmill set in miles goes in as miles. The toggle only changes what your typed number means — switch it and the same figure is now read as miles instead of kilometres — so make sure the unit matches before you read the result. The tool always reports pace in both km and miles regardless, so you never have to convert by hand.

Enter the time across the three boxes — hours, minutes, seconds — exactly as your stopwatch showed it. A 25-minute 5K is hours 0, minutes 25, seconds 0; a two-hour-ten half marathon is hours 2, minutes 10, seconds 0. The boxes add together into one total time, so 0 h 90 m 0 s and 1 h 30 m 0 s mean the same thing — there is no need to tidy ninety minutes into an hour and a half yourself. Put the whole elapsed time in and let the tool carry it.

Read the pace as a time per distance — the minutes and seconds it takes you to cover one unit. A 25-minute 5K comes out at 5:00 per kilometre and 8:03 per mile: the mile pace is the bigger number because a mile is the longer unit, so it takes more time to cover one. This is the figure runners quote to each other and the one you hold on the road, which is why the tool leads with it in both units side by side.

Read the speed as the flip side — how much distance you cover in an hour. The same 25-minute 5K works out to 12 km/h, which is about 7.46 mph. Speed is what a treadmill console and a cyclist think in, so having it next to your pace makes it easy to dial a treadmill to match a target pace, or to compare notes with someone who only ever talks in miles per hour. Pace and speed are two readings of one effort; the tool simply shows you all of them at once.

The formula

Pace and speed are the same effort read two ways — one is time over distance, the other is distance over time, so each is just the other turned upside down:

pace = total time ÷ distance
speed = distance ÷ total time

Worked example with the defaults — 5 km in 25:00. Divide the time by the distance: 25:00 ÷ 5 = 5:00 per km, which is 8:03 per mile (a mile is longer, so it takes more time per unit). Flip it for speed: 5 km ÷ 25 minutes is 12 km/h, about 7.46 mph. The pace per unit does not change with distance — run 10 km in 50:00 and you are still holding 5:00 per km — because pace describes the rate, not the total.

Pace is time per distance (5:00/km) and speed is distance per time (12 km/h); they are the same effort, just inverted, which is why this tool shows both. Runners think in pace, treadmills and cyclists in speed, so it helps to read across — 12 km/h is roughly 7.5 mph, handy when a treadmill only shows mph. The usual way to run a steady distance is even splits: hold one pace the whole way, or aim for a slight negative split with the second half a touch faster, which tends to beat going out too fast and fading. Common race-pace reference points — 5K, 10K, half, and marathon — are exactly the kind of targets you can plug in here to see the pace and speed they demand.

Frequently asked questions

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