🏃 Running Pace Calculator
By ToolNimba Health Team · Reviewed by ToolNimba Editorial Review, running and fitness content · Updated 2026-06-19
This calculator is a planning aid, not coaching or medical advice. It assumes you hold an even pace, which real races rarely deliver because of hills, heat, wind, fatigue, and fueling. Use the figures as a guide, build your training around how you actually feel, and speak to a doctor before starting hard training if you have any health concerns.
Fill in any two fields and leave the third blank, the calculator fills the missing one.
A pace calculator turns the three numbers every runner cares about, distance, time, and pace, into each other. Give it any two and it works out the third. Enter the 5 km you ran and the 25 minutes it took, and it tells you that you held 5:00 per km. Or set a goal pace and a distance and it predicts your finish time. You also get your speed in km/h and mph and projected finish times for the 5K, 10K, half marathon, and marathon at that pace.
What is the Pace Calculator?
Pace is simply time divided by distance: how long it takes to cover one kilometre or one mile. It is the reverse of speed, which is distance over time. Runners usually think in pace (5:00 per km) rather than speed (12 km/h) because pace maps directly onto the splits you read off a watch and the effort you feel on the road. The two carry the same information, so this tool shows both: convert a pace to speed by dividing the distance of one unit by the pace, then scaling to an hour.
The one detail that trips people up is the unit. A pace of 5:00 per km is not the same as 5:00 per mile, because a mile is longer (about 1.609 km). A pace per mile is always a larger number of minutes than the equivalent pace per km, since you are covering more ground per unit. This calculator lets you toggle between minutes per kilometre and minutes per mile, and it keeps the speed readout in both km/h and mph so nothing is lost in translation.
Projecting a finish time from a pace assumes you hold that pace evenly for the whole distance. That is a useful planning model, and it is exactly how the race-time table here is built: multiply your pace per kilometre by the race distance in kilometres. In reality most runners slow over longer events, so a marathon predicted from your 5K pace will usually be optimistic. Endurance fades faster than the simple multiplication suggests, which is why coaches use fade-adjusted models for long races. Treat the marathon figure as a best case and the shorter ones as far more reliable.
When to use it
- Working out the pace you actually held after a run when you know the distance and time.
- Setting a target pace for a goal finish time, for example what per-km pace gives a sub-2-hour half marathon.
- Converting a treadmill speed in km/h or mph into a pace per km or per mile.
- Comparing a friend who trains in min/mile with your own min/km splits on the same scale.
How to use the Pace Calculator
- Choose whether you want pace in minutes per kilometre or minutes per mile.
- Fill in any two of the three fields: distance, time (hours, minutes, seconds), and pace (minutes, seconds).
- Leave the third field blank, the calculator fills it in for you.
- Read off your pace, time, and speed, plus projected finish times for the 5K, 10K, half, and marathon.
Formula & method
Worked examples
You ran 5 km in 25 minutes and want your pace and speed.
- Convert time to seconds: 25 minutes = 1500 seconds
- pace = 1500 ÷ 5 = 300 seconds per km
- 300 seconds = 5 minutes, so pace = 5:00 per km
- speed = 3600 ÷ 300 = 12.00 km/h
- in mph: 12.00 ÷ 1.609344 = 7.46 mph
Result: Pace 5:00 /km, speed 12.00 km/h (7.46 mph)
You target a 1:45:00 half marathon (21.0975 km) and want the pace.
- Convert time to seconds: 1 h 45 min = 6300 seconds
- pace = 6300 ÷ 21.0975 = 298.6 seconds per km
- 298.6 seconds is just under 5 minutes, about 4:59 per km
- speed = 3600 ÷ 298.6 = 12.06 km/h
Result: About 4:59 /km, roughly 12.06 km/h, to finish in 1:45:00
Finish times by pace per km for common race distances (even pace)
| Pace /km | 5K | 10K | Half | Marathon |
|---|---|---|---|---|
| 4:00 | 20:00 | 40:00 | 1:24:23 | 2:48:47 |
| 5:00 | 25:00 | 50:00 | 1:45:29 | 3:30:59 |
| 6:00 | 30:00 | 1:00:00 | 2:06:35 | 4:13:10 |
| 7:00 | 35:00 | 1:10:00 | 2:27:41 | 4:55:22 |
Pace and speed equivalents
| Pace /km | Pace /mile | km/h | mph |
|---|---|---|---|
| 4:00 | 6:26 | 15.00 | 9.32 |
| 5:00 | 8:03 | 12.00 | 7.46 |
| 6:00 | 9:39 | 10.00 | 6.21 |
| 7:00 | 11:16 | 8.57 | 5.33 |
Common mistakes to avoid
- Mixing up per km and per mile. A pace of 5:00 per km is much faster than 5:00 per mile, because a mile is about 1.609 km. Always confirm which unit a pace is quoted in before comparing, and use the toggle here to switch cleanly.
- Trusting a marathon predicted from a short run. Projecting a marathon from your 5K pace assumes you never slow down. Almost everyone fades over 42 km, so the even-pace estimate is a best case. Use it as a ceiling, not a promise.
- Confusing pace with speed. Pace is minutes per distance and speed is distance per hour. A lower pace number means you are faster, while a higher speed number means you are faster, so they move in opposite directions.
- Forgetting seconds when entering time. Typing 25 minutes when you actually ran 25 minutes 30 seconds throws off the pace. Use the seconds box for an accurate result, especially over short distances where a few seconds matter.
Glossary
- Pace
- The time taken to cover one unit of distance, such as minutes per kilometre or minutes per mile.
- Speed
- The distance covered per unit of time, such as kilometres per hour. It is the reciprocal of pace.
- Split
- The time recorded for a portion of a race or run, often per kilometre or per mile.
- Even pace
- Holding the same pace for every part of a run, the assumption behind the finish-time projections here.
- Negative split
- Running the second half of a race faster than the first, a common pacing strategy for strong finishes.
Frequently asked questions
How do I calculate my running pace?
Divide your total time by the distance you covered. For example, 25 minutes over 5 km is 1500 seconds divided by 5, which is 300 seconds, or 5:00 per kilometre. This calculator does it automatically when you enter distance and time.
What is a good running pace per km?
It depends on fitness and distance. Many recreational runners cover a 5K at 6:00 to 7:00 per km, while a 5:00 per km pace (a 25-minute 5K) is a solid intermediate goal. Faster club runners hold well under 4:30 per km over longer races.
How do I convert pace per km to pace per mile?
Multiply your pace per km by 1.609 to get pace per mile, since a mile is about 1.609 km. For example 5:00 per km becomes roughly 8:03 per mile. Use the toggle on this tool to switch between the two instantly.
How fast is a 5:00 per km pace?
A pace of 5:00 per km equals 12.00 km/h, or about 7.46 mph. At that even pace a 5K takes 25:00, a 10K takes 50:00, a half marathon about 1:45:29, and a marathon about 3:30:59.
Can this calculator predict my race finish time?
Yes. Enter a pace and a distance, or read the finish-time table, and it projects times for the 5K, 10K, half, and marathon. The projection assumes an even pace, so longer-race estimates tend to be optimistic since most runners slow down.
Why does my mile pace look slower than my km pace?
A mile is longer than a kilometre, so it takes more time to cover, which makes the per-mile number larger even though you are running at the same effort. A bigger pace number per mile does not mean you got slower.
Sources
- How to Calculate Running Pace , Verywell Fit
- Speed , Encyclopaedia Britannica