Running Pace Calculator
Enter any two of distance, time, and pace to get the third.
- Pace per km
- 5:41
- Pace per mile
- 9:09
- Speed (km/h)
- 10.5
- Speed (mph)
- 6.6
- 400 m track lap
- 2:17
- 200 m half lap
- 1:08
Race splits
These splits assume an even pace.
That is too many splits. Choose a longer split or a shorter distance.
| Distance | Split time | Elapsed |
|---|---|---|
| 5 km | 28:26 | 28:26 |
| 10 km | 28:26 | 56:53 |
| 15 km | 28:26 | 1:25:19 |
| 20 km | 28:26 | 1:53:45 |
| 21.0975 km (Halfway) | 6:15 | 2:00:00 |
| 25 km | 22:12 | 2:22:12 |
| 30 km | 28:26 | 2:50:38 |
| 35 km | 28:26 | 3:19:05 |
| 40 km | 28:26 | 3:47:31 |
| 42.195 km | 12:29 | 4:00:00 |
What if your pace changes by 5 seconds?
| /km | Change (sec) | Difference | Finish time |
|---|---|---|---|
| 5:11 | −30 | −21:17 | 3:38:43 |
| 5:16 | −25 | −17:46 | 3:42:14 |
| 5:21 | −20 | −14:15 | 3:45:45 |
| 5:26 | −15 | −10:44 | 3:49:16 |
| 5:31 | −10 | −7:13 | 3:52:47 |
| 5:36 | −5 | −3:42 | 3:56:18 |
| 5:41 | Current | – | 4:00:00 |
| 5:46 | +5 | +3:19 | 4:03:19 |
| 5:51 | +10 | +6:50 | 4:06:50 |
| 5:56 | +15 | +10:21 | 4:10:21 |
| 6:01 | +20 | +13:52 | 4:13:52 |
| 6:06 | +25 | +17:23 | 4:17:23 |
| 6:11 | +30 | +20:54 | 4:20:54 |
Assumes you hold an even pace over the same distance.
At this fitness, what about other distances?
| Distance | Riegel | Daniels-Gilbert |
|---|---|---|
| 5K | 25:01 | 25:14 |
| 10K | 52:10 | 52:22 |
| Half | 1:55:07 | 1:56:06 |
| Marathon | 4:00:00 | 4:00:00 |
Both formulas assume you have trained for that distance. In a study of recreational runners, Riegel worked well up to the half marathon, but predicted marathon times at least 10 minutes too fast for half of the runners.
Marathon prediction with your training
The Vickers & Vertosick model, built from 2,303 recreational runners, also takes your weekly distance into account.
Half of the runners in the study fell within: 4:20:02 to 4:36:25
Check your times and weekly distance. Two race times must be for different distances.
Adding a second time switches to the more accurate model. The model comes from survey data, with few runners over 60 and participants faster than typical race fields.
Running Pace Calculator
Running Pace Calculator works out distance, time, or pace when you know the other two. It also shows the pace you need for a goal time, splits, and predicted times at other distances.
Pace = finish time ÷ distance
Finish time = pace × distance
Run 5 km in 25 minutes and your pace is 5:00 per km. Hold that pace for a marathon and you finish in about 3 hours 31 minutes.
How to use
- Pick a distance and goal time with the buttons, or type them in. The pace you need appears right away.
- Change the pace or click a pace button to see your finish time. Type numbers only, and the colons appear on their own.
- The 5 sec slower and 5 sec faster buttons show the finish time you will get. Click and hold to keep changing it.
- Click the Splits, Pace changes, and Predictions tabs for what you need. Copy table lets you paste any of them into a note or spreadsheet.
Key terms
Pace
The time it takes to run one kilometer or one mile. A 5:30 pace per km means 5 minutes 30 seconds for each kilometer, and a lower number is faster.
Treadmill speed
Divide 3,600 by your seconds per km.
5:00 pace = 300 seconds
3,600 ÷ 300 = 12 km/h
Prediction formulas
| Formula | How it works |
|---|---|
| Riegel | Multiplies your time by the distance ratio raised to the power of 1.06. |
| Daniels & Gilbert | Uses the oxygen cost of running at a given speed and the intensity you can hold for a given time. |
| Vickers & Vertosick | Used for the detailed marathon prediction. |
On the same validation data, mean squared error was about 381 for Riegel and about 228 for the Vickers & Vertosick (2016) model (208 with two race times). We do not apply the race difficulty adjustment, so enter a time from a typical course.
Which pacing strategy works best?
For recreational runners, even pacing has the most support. These are the results of a 2026 study of 78,912 Boston Marathon finishers.
| Group | Average time |
|---|---|
| Even pacing | 217 minutes |
| Slowed sharply late in the race | 276 minutes |
It is an observational study, so fitter runners may simply pace more evenly.
That is why this calculator builds splits on an even pace. We found no evidence for a specific percentage difference between the two halves, so it does not offer such a plan.
How common is hitting the wall?
In an analysis of more than 4 million race records, 28% of men and 17% of women hit the wall, slowing sharply late in the race. Earlier work by the same author reported that fast starts make hitting the wall more likely.
How much does weather matter?
Ely and colleagues (2007) analyzed seven marathons and found times slowed progressively as wet-bulb globe temperature rose from 5 to 25°C. Slower runners were affected more.
| Wet-bulb globe temperature | Top men, off the course record |
|---|---|
| 5 to 10°C | 1.7% |
| 20 to 25°C | 4.5% |
We could not confirm figures that apply directly to recreational runners, so there is no automatic adjustment. On hot days, allow more margin than these numbers suggest.
FAQ
What pace do I need for a sub-4-hour marathon?
Four hours divided by 42.195 km is about 5:41 per km, or about 9:09 per mile. If your GPS watch reads 1% long, look for about 5:38 per km on its screen.
What pace is a 1-hour 10K?
It is 6:00 per km, which is 10 km/h.
How long are a marathon and a half marathon exactly?
A marathon is 42.195 km (about 26.2 miles), and a half marathon is half of that, 21.0975 km (about 13.1 miles).
Why does my watch show a longer distance than the course?
Certified courses are measured along the shortest route, 0.3 m from the road edge. It is hard to follow that line, and GPS has its own error. Courses also include a small safety margin of 42.2 m over a marathon so they are not short.
Can I predict my marathon from a half marathon time?
Yes, but the Riegel formula tends to predict marathons too fast. Use the prediction on the Predictions tab with your weekly distance for a more realistic number.
Is my input saved?
No. Nothing is saved or sent to a server. The calculation happens only in this browser.
References
- Vickers & Vertosick (2016). An empirical study of race times in recreational endurance runners.
- Smyth (2021). How recreational marathon runners hit the wall.
- Dong & Li (2026). Pacing strategy patterns and performance outcomes in marathon running.
- Ely et al. (2007). Impact of weather on marathon-running performance.
- Daniels & Gilbert (1979). Oxygen Power.
- Riegel (1981). Athletic Records and Human Endurance. American Scientist.