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Training Pace Calculator
Type one pace you already have, measured per kilometre or per mile. This page returns the exact time for each common rep distance, the whole-second time a watch would show, and the difference between the two. It also runs backwards: give it a rep time and it gives you the pace. Both unit systems sit side by side, every formula is printed below, and nothing here tells you how fast you should train.
Exact time for one kilometre at the pace below
5:00.000
8:02.803 per mile · 2:00.000 for 400 m
1. One pace, every rep distance
| Distance | Exact time | Watch shows | Gap |
|---|---|---|---|
| 400 m | 2:00.000 | 2:00 | +0.000 s |
| 1 km | 5:00.000 | 5:00 | +0.000 s |
| 1 mile | 8:02.803 | 8:03 | +0.197 s |
| 5 km | 25:00.000 | 25:00 | +0.000 s |
| 10 km | 50:00.000 | 50:00 | +0.000 s |
Each row is rounded once, on its own. The last row is not forced to agree with the sum of the rows above it.
2. The same pace in both units
| Pace per kilometre | 5:00.000 /km |
|---|---|
| Pace per mile | 8:02.803 /mile |
| Speed | 12.000 km/h · 7.456 mph · 3.333 m/s |
One mile is exactly 1609.344 metres. The mile figure is not a rounded copy of the kilometre figure; it is the same pace expressed in a different unit.
3. Backwards: a rep time becomes a pace
| Pace per kilometre | 5:00.000 /km |
|---|---|
| Pace per mile | 8:02.803 /mile |
| Exact time for one kilometre | 5:00.000 |
This is the reverse of the first table. It uses only the rep time and the rep distance you type.
People reach this page looking for a half marathon mile pace chart, a half marathon time chart, a 1/2 marathon pace chart, or a half marathon pace chart in km. All four names point at the same grid: one table here holds both the kilometre checkpoints and the mile checkpoints, so there is no unit switch and no second chart to open.
Every formula used on this page
Nothing below is a fitted coefficient. Each line is a unit definition or a division you can do by hand.
- sec_per_km = 60 × minutes + seconds, when the pace was entered per kilometre.
- sec_per_km = (60 × minutes + seconds) × 1000 / 1609.344, when the pace was entered per mile.
- sec_per_mile = sec_per_km × 1609.344 / 1000.
- exact_time(d) = sec_per_km × d / 1000, where d is the distance in metres.
- watch_time(d) = round(exact_time(d)), to the nearest whole second.
- gap(d) = watch_time(d) − exact_time(d), printed with its sign so you can see which way the display moved.
- km/h = 3600 / sec_per_km; mph = 3600 / sec_per_mile; m/s = 1000 / sec_per_km.
- reverse: sec_per_km = rep_time / (rep_distance / 1000), then the two pace lines follow from the same unit rules.
Because the mile is defined as exactly 1609.344 metres, the conversion between the two pace columns is exact. The only rounding on this page is the deliberate one in the watch column.
Where the whole-second gap goes
A pace printed as 5:00 per kilometre looks exact, but the time for 400 metres at that pace is 120.000 seconds while the time for one mile is 966.5664 seconds. A display with whole seconds prints 2:00 for the first and 16:07 for the second. The first row has no gap at all; the second has moved by a fraction of a second.
The gap is bounded: rounding to the nearest whole second can move any single row by no more than half a second in either direction. It does not grow with distance, because each row is computed from the pace and its own distance, then rounded once. Adding up the rounded rows of a long rep will therefore not generally reproduce the rounded total, and this page does not force it to.
The gap at this pace: +0.197 s for one mile. This is why the gap column is printed with a sign, and why the exact column is the one to use if you are comparing two paces. Treat the watch column as a display, not as an input to a further calculation.
What a one-way pace tool cannot answer
A calculator that starts from a race result answers one question: given a result, what pace follows. The reverse question — given a pace I already hold, what time should a given rep take, and what result would that pace imply — needs the division printed above, and it is a different entry point rather than a second button on the same form.
Most pace output is a single number in one unit. Here both unit systems are columns of the same answer, the segment times are printed rather than implied, and the rounded display sits next to the exact value with the difference shown. When the formula behind a number is not printed, the number cannot be checked; every formula on this page is printed in the section above.
None of that needs a race result, a fitness model, a training history or a coefficient. The page takes one pace and one distance and returns arithmetic. That is also why it can state plainly what it will not do: there is no model here that could support a recommendation.
Three worked examples, both directions
Forward, kilometres. Enter 5:00 per kilometre. One kilometre takes exactly 300.000 seconds, 400 metres takes 120.000 seconds, and one mile takes 482.803 seconds. The watch column prints 8:03 for the mile, a gap of about +0.197 seconds, while the 400 metres row has no gap at all.
Forward, miles. Enter 8:00 per mile. That is 480 × 1000 / 1609.344 = 298.258 seconds per kilometre, so one kilometre takes about 4:58.258 and the same pace appears in both unit columns without being retyped.
Backwards. A 400 metre rep in 90 seconds is 90 / 0.4 = 225 seconds per kilometre, which is 3:45 per kilometre and about 6:02.2 per mile. The reverse table prints exactly that, using no input other than the rep time and its distance.
What this page deliberately does not do
No training plan, no sessions, no weekly volume and no rest or recovery times. No advice on how fast you should train, no pace zones, and no easy, tempo, threshold or interval labels.
No race prediction and no conversion from a recent race result. No age grading, no sex factors, no weather, heat, humidity or altitude correction. No heart rate, no fatigue model and no negative-split shape.
No GPS drift and no device sync. One kilometre is exactly 1000 metres and one mile is exactly 1609.344 metres. Everything runs in this browser; nothing you type is uploaded.
Every number above is worked out from the four entries you type, in this browser, when you type them. Nothing is uploaded, nothing is saved, and every formula is printed with its arithmetic on this page.
Questions
What is a training pace calculator?
Here it is a two-way arithmetic converter. You enter one pace and it returns the exact time for a set of common rep distances, or you enter a rep time and it returns the pace. It does not decide what pace you should run.
Does this page tell me how fast to train?
No. There are no pace zones, no session labels, no weekly volume and no advice. The pace is an input you bring with you; the page only converts it.
How do I convert minutes per km to minutes per mile?
Multiply the seconds per kilometre by 1609.344 / 1000. One mile is exactly 1609.344 metres. The table above shows both values for the pace you entered, so you can check the multiplication.
Why does my watch show a different time from the exact one?
A watch normally prints whole seconds, so it rounds the exact time. Each row above prints the exact time, the whole-second time and the signed gap. Rounding is applied once per row, not carried into the next row.
Can I work backwards from a rep time?
Yes. Enter the rep time and choose its distance, and the page divides by the distance to return seconds per kilometre and per mile. That is the reverse of the first table.
How exact are the distances on this page?
One kilometre is exactly 1000 metres and one mile is exactly 1609.344 metres. These are unit definitions, not GPS measurements, so no device drift or course shortness is modelled.
What does this page deliberately leave out?
No race-result prediction, no fitness coefficient, no age or sex factors, no weather or altitude correction, no heart rate, no fatigue model, no negative-split shape, and no recovery or rest times.