Enter the distance you ran and your time to get your pace per km and per mile, your average speed, and predicted finish times for 5K, 10K, half marathon and marathon.
Pace formula
Pace = Time ÷ Distance
A 10 km run in 55:00 is a pace of 5:30 per km (8:51 per mile), or 10.9 km/h.
Race time predictions
Predictions use Riegel’s formula, a long-standing rule of thumb for endurance events:
T2 = T1 × (D2 ÷ D1)^1.06
It assumes you are equally well trained for the longer distance. Predictions from a 5K to a marathon are optimistic for most runners who haven’t done long training runs.
Common finish times and paces
| Goal | Pace per km | Pace per mile |
|---|---|---|
| 5K in 25:00 | 5:00 | 8:03 |
| 10K in 50:00 | 5:00 | 8:03 |
| Half marathon in 2:00:00 | 5:41 | 9:09 |
| Marathon in 4:00:00 | 5:41 | 9:09 |
| Marathon in 3:30:00 | 4:59 | 8:01 |
Training tips
- Most training runs should be at an easy, conversational pace – often 60–90 seconds per km slower than race pace.
- Increase weekly distance gradually (roughly 10% a week is a common guideline).
- Hydration matters on long runs – see the water intake calculator.
Pace chart
| Pace /km | Pace /mile | 5K | 10K | Half | Marathon |
|---|---|---|---|---|---|
| 4:00 | 6:26 | 20:00 | 40:00 | 1:24:23 | 2:48:47 |
| 4:30 | 7:15 | 22:30 | 45:00 | 1:34:56 | 3:09:53 |
| 5:00 | 8:03 | 25:00 | 50:00 | 1:45:29 | 3:30:59 |
| 5:30 | 8:51 | 27:30 | 55:00 | 1:56:02 | 3:52:04 |
| 6:00 | 9:39 | 30:00 | 1:00:00 | 2:06:35 | 4:13:10 |
| 7:00 | 11:16 | 35:00 | 1:10:00 | 2:27:41 | 4:55:22 |
These are even-pace finish times. Real races usually include a slower start in the crowd and hills, so plan a small buffer.
Training paces from a recent race
Many coaches set training zones relative to your current 5K or 10K pace:
- Easy runs: about 60–90 seconds per km slower than 5K pace – you can hold a conversation.
- Tempo runs: roughly your 10K–half-marathon pace, “comfortably hard”, for 20–40 minutes.
- Intervals: around 5K pace or a little faster, in repeats of 400 m to 1 km with recovery jogs.
- Long runs: easy pace, building gradually to 30–35 km for marathon training.
Treadmill speeds
Treadmills show speed rather than pace. Divide 60 by your pace in minutes to get km/h (5:00/km → 12 km/h) or mph (8:00/mile → 7.5 mph). Setting a 1% incline roughly compensates for the lack of wind resistance.
Why your race prediction may be off
- Riegel’s formula assumes you’ve trained for the longer distance – marathon predictions from a 5K are often 5–10% too fast for newer runners.
- Heat, humidity, hills and altitude slow everyone down.
- Pacing matters: starting too fast is the most common reason for a slow finish.
Real-life scenarios
- First 5K: Emma ran 5 km in 32:30 – a pace of 6:30 per km (10:28 per mile). To break 30 minutes she needs 6:00 per km, so her training runs include short intervals at that pace.
- Half-marathon goal: Raj wants 1:59:59. The calculator shows he needs 5:41 per km. His recent 10K in 52:00 predicts about 1:55, so the goal is realistic with a few long runs.
- Treadmill runner: Lena’s watch shows 9:00 per mile. Dividing 60 by 9 gives 6.7 mph – the speed to set on the treadmill.
- Marathon pacing band: For a 4:30 marathon, the pace is 6:24 per km. Writing down split times at 5 km intervals helps avoid starting too fast.
Pace vs speed
Runners talk in pace (minutes per km or mile) because it maps directly to splits on a watch. Cyclists and treadmills use speed (km/h or mph). They’re the same information: speed = 60 ÷ pace. A 5:00/km pace is 12 km/h; a 10:00/mile pace is 6 mph.
Related calculators
- Water intake calculator – hydration needs including exercise
- Sleep calculator – bedtimes for recovery
- Days between dates – days until race day
FAQs
What pace is a 2-hour half marathon?
5:41 per km or 9:09 per mile.
What is a sub-4 marathon pace?
5:41 per km (9:09 per mile) or faster – the same pace as a 2-hour half marathon held for twice the distance.
What is a good 5K time?
For recreational runners, finishing in 25–35 minutes is common. Under 25 minutes is a solid amateur time.
How do I convert km pace to mile pace?
Multiply the pace per km by 1.609. The calculator does it for you.