Running pace calculator — pace, time and distance
Convert running pace, speed, time and distance for 5K, 10K, half and full marathon, with a kilometre or mile split table you can copy.
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Split tables assume an even effort on flat ground. Hills, heat, wind and altitude all move real times, and race predictions assume you have actually trained for the longer distance.
| Split | Cumulative | Segment |
|---|---|---|
| 1 km | 0:05:00 | 5:00 |
| 2 km | 0:10:00 | 5:00 |
| 3 km | 0:15:00 | 5:00 |
| 4 km | 0:20:00 | 5:00 |
| 5 km | 0:25:00 | 5:00 |
| 6 km | 0:30:00 | 5:00 |
| 7 km | 0:35:00 | 5:00 |
| 8 km | 0:40:00 | 5:00 |
| 9 km | 0:45:00 | 5:00 |
| 10 km | 0:50:00 | 5:00 |
| Race | Predicted time | Pace / km | Pace / mile |
|---|---|---|---|
| 5K | 0:23:59 | 4:48 | 7:43 |
| 10K | 0:50:00 | 5:00 | 8:03 |
| Half marathon | 1:50:19 | 5:14 | 8:25 |
| Marathon | 3:50:01 | 5:27 | 8:46 |
The formula, with your numbers
- Pace
- 0:50:00 ÷ 10 km = 5:00 per km
- Pace conversion
- 5:00 per km × 1.609344 = 8:03 per mile
- Speed
- 10 km ÷ 0.8333 h = 12 km/h
- Riegel prediction
- T₂ = T₁ × (D₂ ÷ D₁)^1.06
The 1.06 exponent is what makes the prediction realistic: doubling the distance costs more than double the time, because pace has to drop.
What this means
5:00 per kilometre — 8:03 per mile — is 12 km/h or 7.46 mph. Holding it for 10 km gives 0:50:00.
On the track that is 2:00 per 400 m lap, which is the easiest way to check whether the pace actually feels right before you commit to it in a race.
The equivalents above assume you have trained for the distance in question. Moving up from 5K to a marathon on 5K training will not deliver the predicted time — treat the longer predictions as a ceiling and the shorter ones as realistic.
How to use the pace calculator
- Choose what you want to solve for: pace from a distance and time, a finish time from a target pace, or how far you covered at a known pace.
- Pick a standard distance or enter your own. Metric and imperial paces are shown side by side either way.
- Fill in the other two values. Everything updates as you type — there is no calculate button.
- Use the split table to plan a race, and the equivalent-times table to see what the performance predicts at other distances.
Pace, speed and how they relate
Pace is time per unit of distance; speed is distance per unit of time. They are reciprocals, and runners think in pace because a target pace is something you can hold.
- Pace (min/km) = total time in minutes ÷ distance in km
- Pace (min/mile) = pace per km × 1.609344
- Speed (km/h) = 60 ÷ pace in min/km
- Speed (mph) = 60 ÷ pace in min/mile
A quick mental conversion: to go from min/km to min/mile, add about 60 percent. 5:00/km becomes roughly 8:00/mile (exactly 8:03). 6:00/km becomes about 9:39/mile.
Common pace to speed conversions
| Pace / km | Pace / mile | km/h | mph |
|---|---|---|---|
| 3:00 | 4:50 | 20.0 | 12.4 |
| 3:30 | 5:38 | 17.1 | 10.6 |
| 4:00 | 6:26 | 15.0 | 9.3 |
| 4:30 | 7:15 | 13.3 | 8.3 |
| 5:00 | 8:03 | 12.0 | 7.5 |
| 5:30 | 8:51 | 10.9 | 6.8 |
| 6:00 | 9:39 | 10.0 | 6.2 |
| 6:30 | 10:28 | 9.2 | 5.7 |
| 7:00 | 11:16 | 8.6 | 5.3 |
| 8:00 | 12:52 | 7.5 | 4.7 |
Target paces for common goal times
| Goal | Distance | Pace / km | Pace / mile |
|---|---|---|---|
| Sub-20 5K | 5 km | 3:59 | 6:26 |
| Sub-25 5K | 5 km | 4:59 | 8:02 |
| Sub-30 5K | 5 km | 5:59 | 9:39 |
| Sub-45 10K | 10 km | 4:29 | 7:14 |
| Sub-50 10K | 10 km | 4:59 | 8:02 |
| Sub-2:00 half | 21.0975 km | 5:41 | 9:09 |
| Sub-1:45 half | 21.0975 km | 4:58 | 8:00 |
| Sub-1:30 half | 21.0975 km | 4:16 | 6:52 |
| Sub-4:00 marathon | 42.195 km | 5:41 | 9:09 |
| Sub-3:30 marathon | 42.195 km | 4:58 | 8:00 |
| Sub-3:00 marathon | 42.195 km | 4:16 | 6:52 |
A neat coincidence worth remembering: the pace for a sub-two-hour half marathon and a sub-four hour marathon is the same, 5:41/km. Likewise sub-1:45 half and sub-3:30 marathon both need 4:58/km. Doubling the distance at the same pace exactly doubles the time — which is precisely why it is so much harder than it looks.
Predicting race times across distances
Pete Riegel's 1977 formula is the standard tool:
T₂ = T₁ × (D₂ ÷ D₁)1.06
The exponent of 1.06 is what makes it realistic. If it were 1.00, doubling the distance would double the time. At 1.06, doubling the distance costs about 4.2 percent more than double — because pace has to drop as distance grows.
It works best when the two distances are within a factor of about four of each other, and when you have actually trained for the longer one. Predicting a marathon from a 5K on 5K mileage will flatter you badly: marathon performance depends on fuelling, durability and long-run volume that a 5K cannot measure. Predicting a 10K from a half marathon, by contrast, is usually accurate to within a minute.
Even splits, negative splits and the wall
The split table on this page assumes even pacing. That is the right default: almost every distance world record has been set with even or slightly negative splits, and going out too fast is the most common reason for a bad race.
A negative split means running the second half faster than the first. Practically, that means starting 5 to 10 seconds per kilometre slower than target for the first two or three kilometres, settling into target pace, and spending whatever is left in the last quarter. It feels frustratingly slow at the start. It almost always produces a faster finish time.
In the marathon, "the wall" around 30–32 km is largely glycogen depletion. Even pacing plus 30 to 60 g of carbohydrate per hour from the start moves it a long way back, and often removes it entirely.
What moves your real pace
- Hills. Roughly 12–20 seconds per kilometre slower per 1 percent of gradient uphill, and about half that back on the way down. Rolling courses are always slower than flat ones.
- Heat. Above about 15 °C, expect to lose 2 to 5 percent on marathon pace, more if humidity is high.
- Wind. A headwind costs far more than the equivalent tailwind gives back. Tuck in behind someone if you can.
- Altitude. Above 1,500 m, endurance pace drops noticeably until you acclimatise, which takes two to three weeks.
- Surface. Trail and soft ground can cost 30 to 60 seconds per kilometre against tarmac at the same effort.
Which is why pace is a plan, not a promise. Run the first half on effort, check it against the split table, and adjust.
Questions
How do I convert min/km to min/mile?
Multiply the pace in minutes per kilometre by 1.609344. A 5:00/km pace is 8:03/mile; a 6:00/km pace is 9:39/mile. The calculator shows both at once so you never have to do it by hand.
What pace do I need for a sub-4-hour marathon?
5:41 per kilometre, or 9:09 per mile, held for the full 42.195 km. Sub-3 needs 4:16/km (6:52/mile) and a sub-2-hour half needs 5:41/km — the same pace as a four-hour marathon.
How does the race-time prediction work?
It uses Riegel’s formula, T2 = T1 x (D2 / D1) raised to the power 1.06. It is a good guide when the distances are within roughly a factor of four and you have trained for the longer one, and optimistic otherwise.
What is a negative split?
Running the second half of a race faster than the first. It is how most road records are set, and the split table here lets you plan one by aiming a few seconds per kilometre slower than target early on.