🏃 Pace Calculator
Give the calculator any two of distance, time and pace and it works out the third — in miles or kilometres.
📖 Popular goal times and the pace they need
| Race | Goal time | Pace / km | Pace / mile |
|---|
Pace is written as minutes:seconds per unit — 5:00/km means five minutes for every kilometre, which is 12 km/h. One mile is about 1.609 kilometres, so mile pace is always the larger number: 5:00/km is roughly 8:03/mile.
How to use the Pace Calculator
Enter a distance and a target time, or a distance and a pace, to see finish times across common race distances.
How it works
Pace is time divided by distance, usually expressed in minutes per kilometre or per mile. Converting pace across distances assumes an even effort throughout, so a 5K pace multiplied by roughly 2.9 approximates half-marathon pace. The relationship is not exact because endurance performance scales slightly less than linearly with distance.
When to use it
Use it to check whether a target finish time is realistic, to plan pacing for a race, and to compare two goal times on an even footing.
Worked example
Pace versus finish time across distances:
| Distance | at 6:00/km | at 5:00/km | at 4:30/km |
|---|---|---|---|
| 5K | 30:00 | 25:00 | 22:30 |
| 10K | 1:00:00 | 50:00 | 45:00 |
| Half marathon | 1:45:00 | 1:26:00 | 1:17:00 |
| Marathon | 3:30:00 | 2:50:00 | 2:33:00 |
Assumptions and limitations
Race conditions rarely allow even pacing: starts are congested, fades happen in the second half, and heat, wind and terrain all matter. Beginner runners are typically 5 to 15 percent slower than standard prediction formulas suggest. This is a training aid, not coaching or medical advice.
Frequently Asked Questions
What pace do I need to run a 4-hour marathon?
A marathon is 26.2188 miles, and four hours is 14,400 seconds, so 14,400 ÷ 26.2188 gives about 549 seconds — 9:09 per mile, or 5:41 per kilometre. The same 9:09 mile pace also finishes a half marathon in just over 2 hours, which is why breaking 2:00 in the half is the classic stepping stone to a sub-4 marathon.
Why is my race pace slower than my training pace?
Three usual suspects: going out too fast with the crowd and fading, under-fuelling, and a course with hills or heat. Training with even-paced efforts and a fast finish teaches you what goal pace actually feels like. On race day, deliberately hold back for the first two miles — negative splits (second half faster than the first) are the mark of a well-executed race.
Should I train by pace or by heart rate?
Both, for different jobs. Heart rate controls intensity on easy days — most runners should keep easy runs around 65–75% of maximum heart rate. Pace is the right tool for race-specific work: interval targets, tempo runs and race-day execution. If the two disagree on a hot or hilly day, trust heart rate and effort over the watch's pace number.
Is treadmill pace the same as outdoor pace?
No — the treadmill has no wind resistance and a perfectly smooth belt, so the same speed feels easier. Many coaches suggest a 1% incline to bring treadmill effort in line with outdoor running. Also note that treadmills usually show speed rather than pace; convert with pace (sec per mile) = 3600 ÷ speed (mph) before comparing to a road race result.
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