Running Pace Calculator
Fill in any two of pace, time and distance, and the third follows. Everything is entered and returned in minutes and seconds, because a pace of 5.5 minutes per kilometre is 5∶30 — and reading it as 5∶50 puts every split twenty seconds out.
Fill any two
The one you pick becomes the answer; the other two become the inputs.
Pace is per kilometre, and the race markers convert to match.
How far you ran, or plan to. A marathon is 42.195 km.
Whole minutes per kilometre — the part before the colon.
The part after the colon. 5∶30 is 5 and 30, never 5.5.
10 km at 5:30 per kilometre takes 55:00. Held all the way to a marathon, the same pace is 3:52:04.
- Pace
- 5:30 per km
- Speed
- 10.91 km/h
- Treadmill
- 6.78 mph = 8:51 /mi
- Finish time
- 55:00
- Distance
- 10 km
| Distance | Race | Elapsed |
|---|---|---|
| 1 km | — | 5:30 |
| 2 km | — | 11:00 |
| 3 km | — | 16:30 |
| 4 km | — | 22:00 |
| 5 km | 5K | 27:30 |
| 6 km | — | 33:00 |
| 7 km | — | 38:30 |
| 8 km | — | 44:00 |
| 9 km | — | 49:30 |
| 10 km | 10K | 55:00 |
| 21.0975 km | Half marathon | 1:56:02 |
| 42.195 km | Marathon | 3:52:04 |
| Race | Predicted time |
|---|---|
| 5K | 26:23 |
| 10K | 55:00 |
| Half marathon | 2:01:21 |
| Marathon | 4:13:01 |
One relationship, rearranged three ways
Pace, time and distance are a single equation. Name any two and the third is fixed — there is no modelling, no fitted curve and nothing to disagree with.
t = p × d • p = t ÷ d • d = t ÷ p- t
- Elapsed time, in seconds
- p
- Pace, in seconds per kilometre or per mile
- d
- Distance, in the same unit the pace uses
The engine behind this page works entirely in seconds and never handles a minutes value at all. Minutes exist only in the two input boxes and in the display, and the conversion between the two happens in exactly one function — which is why the headline figure, the breakdown and the splits table can never disagree about what 330 seconds means.
Speed is the same relationship inverted: 3600 ÷ pace. A pace of 330 seconds per kilometre is 10.91 km/h. Runners talk in pace and cyclists in speed, and the two are the same number upside down.
The Equivalent race times table below is the one exception: predicting a different distance from a held pace needs a fitted curve, because fatigue is not linear the way multiplication is. That formula, and where its exponent comes from, is covered separately in the sources below rather than here.
10 km at 5∶30 per kilometre
A pace of 5 minutes 30 seconds is 330 seconds. Ten kilometres at 330 seconds each is 3,300 seconds, and 3,300 seconds is 55 minutes exactly — so the finish time is 55∶00, with the 5K marker passed at 27∶30 and every kilometre marker 5∶30 after the last.
Run the same arithmetic out to the race distances and the marathon row reads 42.195 × 330 = 13,924 seconds, or 3∶52∶04. That figure is arithmetically correct and physiologically optimistic. Riegel’s endurance formula — 55∶00 × (42.195 ÷ 10)1.06 — puts the same runner at about 4∶13∶01, twenty-one minutes slower, and the gap is not an error in either calculation. It is what fatigue costs over four hours, and no amount of multiplication can see it.
Turn the question around and the answers stay consistent. Ask for the pace instead — 55∶00 over 10 km — and you get 330 seconds, 5∶30, not the 5.5 a keypad shows. Ask for the distance from 55∶00 at 5∶30 and you get 10 km back.
Every one of those figures is on the page without further arithmetic. Open the breakdown and Treadmill reads 6.78 mph — 8∶51 per mile — the same 5∶30-per-kilometre effort re-expressed for a console that only takes mph. Below the splits table, Equivalent race times carries the same 55∶00 out to all four standard distances via Riegel, so the 4∶13∶01 marathon figure above is read off the page rather than recomputed by hand. Open Advanced options and set the splits table to miles instead, and the 5K row moves from 27∶30 at the 5 km marker to 27∶30 at 3.1069 mi — the same instant in the run, named in a different unit.
What this calculator assumes
- The pace holds. Every row of the splits table is one pace multiplied by one distance. Most runners positive-split — the second half is slower than the first — so the table is a target to run against, not a prediction of what the watch will say.
- No fatigue, terrain or weather model. Hills, heat, wind, altitude and how long you have been training are all absent. Two runners with the same 10K pace can be an hour apart over a marathon.
- The distance is the course distance. Races are measured along the shortest legal route; a GPS watch records the line you actually ran, which is longer. A watch reading 42.5 km at the end of a marathon is normal and means your true pace was slightly faster than the watch reported.
- Whole seconds. Results are rounded to the second, which is how paces and finish times are quoted everywhere outside a track meet. A mid-table row can therefore sit one second away from a hand multiplication of the displayed pace; the finish row always matches the total.
- The mile is exactly 1609.344 metres. That has been the definition since 1959, so switching units introduces no error of its own.
- Riegel’s exponent is fixed, not personal. The equivalent race times use the same 1.06 for every runner, fitted to world-record and age-group performances across running, walking and swimming lasting roughly 3.5 minutes to just under four hours. A runner who is undertrained for the longer distance will fade by more than the formula predicts; one who is specifically endurance-trained can beat it.
- A treadmill’s mph is not quite outdoor pace. The Treadmill figure in the breakdown is a straight unit conversion — seconds per mile turned into miles per hour — not an effort adjustment. A moving belt removes the air resistance an outdoor runner pushes against, which is why many treadmill runners add a 1% incline to compensate; this calculator does not add one for you.
Running pace FAQ
Why is 5.5 minutes per kilometre 5∶30 and not 5∶50?
Because time is counted in sixties, not tens. Half a minute is 30 seconds, so 5.5 minutes is 5 minutes 30 seconds. The decimal 0.5 and the clock 50 look alike and mean different things — 5∶50 would be 5.833 minutes. This is the single most common error in pace arithmetic, and it is why this calculator never asks for or shows a decimal minute: you enter minutes and seconds in separate boxes, and every figure it returns is already in m∶ss.
Why is a marathon 42.195 km rather than a round number?
It is 26 miles 385 yards, which is the length of the 1908 Olympic course in London, from Windsor to the stadium at White City. That distance was adopted as the standard marathon in 1921 and has not moved since — so the metric figure is a conversion of an imperial oddity, and the imperial figure is an oddity because of how one particular course happened to be laid out. The half is exactly half of it: 21.0975 km, or 13 miles 192.5 yards.
Can I predict my marathon time from a 10K pace?
Not by multiplying, which is all the splits table does. Hold 5∶30 per km for 10 km and you finish in 55∶00; multiply that pace out to 42.195 km and you get 3∶52∶04, and almost nobody runs that. The Equivalent race times table below the splits — Pete Riegel's endurance formula, old time × (new distance ÷ old distance) raised to the power 1.06 — puts the same runner nearer 4∶13∶01, and even that assumes the marathon training to back it up. Treat the splits table as a pace target and the predictions table as a formula's best guess, not a forecast either one can keep.
What is a negative split, and why is it rare?
A negative split is running the second half of a race faster than the first. Most runners do the opposite: they start faster than planned, and fatigue, heat and hills take the pace back later. That is why an even-pace table is best read as the line you are trying not to drift above — a race run 10 seconds per kilometre too fast for the first 10 km rarely gets those seconds back.
How do I convert a pace per kilometre into a pace per mile?
Multiply by 1.609344, the exact number of kilometres in a mile. 5∶30 per kilometre is 330 seconds, and 330 × 1.609344 is 531 seconds, which is 8∶51 per mile. Switching the unit toggle above does this for you, but it also reinterprets the distance you typed — 10 becomes 10 miles, not 10 kilometres — so check that field after you switch. To keep the pace and distance in kilometres but only see the splits table in miles, use the splits table unit in Advanced options instead.
What treadmill speed matches my running pace?
Divide 3600 by your pace in seconds per mile. 5∶30 per kilometre is 531 seconds per mile once converted, and 3600 ÷ 531 is 6.78 — so 6.78 mph is what to key into the console. The breakdown below now shows this as a Treadmill line, in mph and per-mile pace together, whatever unit you paced in. It is a straight unit conversion, not an effort adjustment: a moving belt removes the air resistance an outdoor runner pushes against at the same pace, which is why many treadmill runners add a 1% incline to compensate. This calculator does not add that incline for you.
Can I see my splits in miles if I paced in kilometres?
Yes — open Advanced options and set the splits table unit independently of the pace above. The headline, breakdown and equivalent race times all stay in whichever unit you paced in; only the splits table's rows and markers switch, which is useful when you train in one unit but the race you are pointing the pace at is measured in the other.
Sources and review notes
- World Athletics — the competition rules that fix the standard road distances, including the marathon at 42.195 km and the half at 21.0975 km
- NIST Special Publication 811 — the international mile as exactly 1609.344 metres, which is the only conversion factor this tool uses
- Riegel, P.S. (1981), “Athletic Records and Human Endurance,” American Scientist 69(3): 285–290 — the endurance formula behind the Equivalent race times table, fitted to world-record and age-group performances across running, walking and swimming
The pace, splits and treadmill figures have no data behind them to go stale: a multiplication, a division, and one exact unit conversion. The Equivalent race times table is different — it applies a single fitted exponent from the Riegel paper above to every runner alike, which is a genuine empirical claim rather than arithmetic, and is the one figure on this page a better dataset could someday revise.