Your Half marathon splits
| Split | Split time | Pace | Elapsed |
|---|
A pace on paper needs a plan to hit it. The Running Genie builds your half marathon plan around this goal and adjusts it from every run you log: App Store · Google Play
How the half marathon calculator works
A half marathon is 21.0975 km (13.1 miles). Your average pace is your finish time divided by that distance, so a 2:00:00 half needs 5:41 per km. Choose what you know: a goal time, a pace you can hold, or a recent race result.
Predictions use the Riegel formula with an exponent of 1.06, the same model as our race time predictor. Splits can be even or a 1–3% negative split, where the second half runs faster than the first and the halves still add up to your goal.
Half marathon pace chart
Pace per km and per mile for common half marathon goal times.
| Goal time | Pace / km | Pace / mile | km/h |
|---|---|---|---|
| 1:30:00 | 4:16 | 6:52 | 14.1 |
| 1:40:00 | 4:44 | 7:38 | 12.7 |
| 1:45:00 | 4:59 | 8:01 | 12.1 |
| 1:50:00 | 5:13 | 8:23 | 11.5 |
| 1:55:00 | 5:27 | 8:46 | 11.0 |
| 2:00:00 | 5:41 | 9:09 | 10.5 |
| 2:10:00 | 6:10 | 9:55 | 9.7 |
| 2:15:00 | 6:24 | 10:18 | 9.4 |
| 2:20:00 | 6:38 | 10:41 | 9.0 |
| 2:30:00 | 7:07 | 11:27 | 8.4 |
| 2:45:00 | 7:49 | 12:35 | 7.7 |
| 3:00:00 | 8:32 | 13:44 | 7.0 |
Tips for pacing a half marathon
- Start controlled: the first 5 km should feel easy at goal pace. Banking time early usually costs more later.
- Run the tangents: GPS often reads 0.1–0.3 km long over a half, so check your splits against the course markers.
- Fuel for the second half: runners finishing beyond about 1:30 often take a gel around 45–60 minutes in.
- Test your pace in training: include a few miles at goal pace inside your long runs before race day.
Turn your goal time into a half marathon plan
The Running Genie builds a half marathon plan from your goal time and current fitness, sets your easy, tempo and long-run paces, and adapts the plan as your runs come in.
Frequently asked questions
How long does it take to run a half marathon?
It depends on your pace. A half marathon is 21.0975 km (13.1 miles). At 5:00 per km it takes 1:45:29, at 6:00 per km 2:06:35, and at 7:00 per km 2:27:41. Enter your own pace above to get your finish time.
What pace do I need for a sub-2 hour half marathon?
You need to average 5:41 per km (9:09 per mile). GPS watches usually measure a race slightly long, so many runners aim a few seconds per km faster than this.
How do I predict my half marathon time from a 5K or 10K?
This calculator uses the Riegel formula, T2 = T1 × (D2 / D1)^1.06. A 25:00 5K predicts about 1:55:00 for the half, and a 50:00 10K predicts about 1:50:19. The prediction assumes you have done the long runs for the distance.
Should I run even or negative splits in a half marathon?
Even pacing or a small negative split usually gives the best result. Starting too fast costs more time late in the race than it gains early. Use the pacing option above to see splits for a 1–3% negative split.
How far is a half marathon in miles?
A half marathon is 13.1 miles (21.0975 km). The calculator shows mile splits, including the final 0.1 mile, when you choose mile splits.
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Train for the time you just calculated
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