Running Pace Calculator

What is running pace?

Running pace is how long it takes you to cover one unit of distance, written as minutes and seconds per kilometre or per mile. A pace of 5:00 per km means every kilometre takes five minutes. A smaller number is a faster run.

Pace is the number runners plan with, because races are measured in kilometres or miles and a watch shows time. If you know your pace, you know what the clock should say at every marker.

How do I calculate running pace?

Divide your time by your distance. The running pace calculator above does this for you, but the working is simple enough to do by hand:

1. Convert the time to seconds. 25:00 is 25 × 60 = 1,500 seconds.
2. Divide by the distance. 1,500 ÷ 5 km = 300 seconds per km.
3. Convert back to minutes and seconds. 300 seconds = 5:00 per km.

The same run in other units: 300 × 1.609344 = 482.8 seconds, so 8:03 per mile; and 3,600 ÷ 300 = 12 km/h, which is 7.46 mph.

Running pace formula

Distance, time and pace are tied together. Know any two and you can find the third.

The calculator keeps every value in metres and seconds internally and rounds only when it shows the result, so converting back and forth does not add rounding errors.

Pace vs speed: what is the difference?

They are the same measurement written two ways. Pace is time per distance (min/km). Speed is distance per time (km/h). To convert, divide 60 by the other one: a 6:00 per km pace is 60 ÷ 6 = 10 km/h, and 12 km/h is 60 ÷ 12 = 5:00 per km.

Seconds need one extra step. A pace of 5:30 is 5.5 minutes, not 5.3, so 60 ÷ 5.5 = 10.91 km/h. Forgetting this is the most common conversion mistake.

Pace per kilometre vs pace per mile

A mile is exactly 1.609344 km, so a pace per mile is always about 61% longer than the same pace per km. Multiply a per-km pace by 1.609344 to get the per-mile pace; divide to go the other way.

Runners in the United States mostly train and race in miles. In the United Kingdom both are common: road signs and many marathons use miles, while parkrun and track events use kilometres and metres. Canada, Australia and New Zealand mostly use kilometres. Race names such as 5K, 10K and the marathon (42.195 km, 26.2 miles) are the same everywhere. The calculator shows both units in every result, so you do not have to pick one.

How do I calculate finish time and distance?

Finish time is pace multiplied by distance. At 6:00 per km, 10 km takes 60 minutes; a half marathon takes 6 × 21.0975 = 126.6 minutes, which is 2:06:35. Use the Time mode.

Distance is time divided by pace. Forty-five minutes at 6:00 per km is 45 ÷ 6 = 7.5 km (4.66 miles). Use the Distance mode — handy when a plan says "run 45 minutes easy" and you want to know how far that is.

What pace do I need for my target time?

Divide the goal time by the race distance. In the Pace mode, pick the race and type your target finish time. The table below shows the finish time for each race at a steady pace. It is plain arithmetic — a constant-pace projection, not a prediction of what you can run.

5K pace

A 5K is 5 km or 3.107 miles. A 25-minute 5K needs 5:00 per km (8:03 per mile). A 30-minute 5K needs 6:00 per km (9:39 per mile), and a 20-minute 5K needs 4:00 per km (6:26 per mile).

10K pace

A 10K is 6.214 miles. Fifty minutes needs 5:00 per km; an hour needs 6:00 per km (9:39 per mile); 45 minutes needs 4:30 per km (7:15 per mile).

Half marathon pace

The half marathon is 21.0975 km (13.1 miles). A two-hour half needs just under 5:41 per km, or 9:09 per mile. A 1:45 half needs about 4:59 per km (8:01 per mile).

Marathon pace

The marathon is 42.195 km (26.2 miles). A four-hour marathon needs the same 5:41 per km (9:09 per mile) as a two-hour half, held for twice as long. A 3:30 marathon needs about 4:59 per km. Course measurement follows the shortest possible line, so most runners cover slightly more than 42.195 km on the day; a few seconds per kilometre in hand is sensible.

How do I calculate running splits?

A split is the time for one section of a run — usually each kilometre or mile. The cumulative time is the running total at each marker. With an even pace, each split is pace × section length and each cumulative time is pace × distance so far. The Splits mode builds the full table for any distance and lets you copy it.

Even vs negative vs positive splits

• Even splits: the same pace from start to finish.
• Negative splits: the second half is faster than the first.
• Positive splits: the second half is slower than the first.

The calculator models the last two as a planning scenario: you choose how many percent the first half differs from the average, the second half mirrors it, and the finish time stays exactly the same. It shows the arithmetic of a plan. It does not claim that one strategy is best for you or for a given course.

Race time prediction and the Riegel formula

The Predictor mode estimates a time at one distance from a recent result at another. It uses the formula published by Peter Riegel in 1981:

T1 and D1 are your known time and distance, D2 is the target distance and T2 the estimate. The exponent 1.06 means pace slows by about 4% each time the distance doubles. Example: 10 km in 50:00 gives a half marathon of 3,000 × (21.0975 ÷ 10)^1.06 = 6,619 seconds, or 1:50:19.

Treat it as a model-based estimate. It assumes you are equally trained for both distances. It works best between similar distances. A 2016 study of recreational runners (Vickers and Vertosick) found the formula reasonable up to the half marathon but too optimistic for the marathon for many runners. Endurance, terrain, weather and pacing all move the real result. You can change the exponent on the page if you know a value that fits your own results better.

Treadmill pace and speed

Treadmills show speed, while training plans usually give pace. Divide 60 by the speed to get pace: 10 km/h is 6:00 per km, 12 km/h is 5:00 per km, 6.0 mph is a 10:00 mile and 7.5 mph is an 8:00 mile. The Treadmill mode converts both ways and has buttons for common belt speeds. It converts units only; it does not adjust for incline or for the difference between a belt and the road.

Running pace chart

The Pace chart mode lists pace per km, pace per mile, km/h and mph side by side. Choose the fast range, the normal range or set your own, and copy the table if you want it in a spreadsheet.

Common running pace mistakes

• Treating seconds as decimals. 5:30 is 5.5 minutes, not 5.3.
• Mixing units. A pace from a km-based plan entered as a per-mile pace is 61% off. Check the unit next to every field.
• Using a rounded distance. A half marathon is 21.0975 km, not 21; a marathon is 42.195 km, not 42.
• Reading a projection as a prediction. "Marathon at 5:00 per km = 3:30:59" only says what the clock shows if that pace is held. Whether you can hold it is a training question.
• Trusting GPS pace blindly. Instant pace on a watch jumps around under trees and between buildings. Lap averages are steadier.

Methodology and limits

• All values are held in metres and seconds. One mile is exactly 1,609.344 m and one yard exactly 0.9144 m.
• Times are rounded to whole seconds for display only. In split tables, cumulative times are rounded first and each split is the difference between two of them, so the last row always equals the finish time.
• Inputs are limited to 1 m – 1,000 km, up to 999 hours, and paces between 1:00 and 60:00 per km. Anything outside gets a clear message rather than a meaningless number.
• The calculator does arithmetic. It does not assess fitness or health, prescribe training paces, or adjust for heat, wind, hills or altitude — there is no single validated formula for those, so none is offered.
• Everything runs in your browser. Nothing you type is sent to a server or stored.