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Browse all calculatorsEnter any two of pace, time and distance to get the third, with km and mile splits.
This assumes an even pace, which real runs rarely keep. This is a general estimate for educational use. It is not medical advice, a diagnosis or a training plan. Talk to a doctor or other qualified professional before you change your exercise or health care.
| Split | Total time | Split time |
|---|
| Unit | Value |
|---|
| Distance | Time |
|---|
Riegel formula: T2 = T1 × (D2 ÷ D1)^1.06, using the time and distance above as T1 and D1. It is a rough estimate from one result and ignores course, weather and training.
| Distance | Time | Per km | Per mile |
|---|
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Pace is the time it takes to cover one unit of distance, usually minutes per kilometre or per mile. Divide time by distance to get pace, divide time by pace to get distance, or multiply pace by distance to get the finish time. This pace calculator solves any one of the three from the other two.
The answer updates as you type, in km or miles, with splits, a pace and speed table and an optional race time estimate below it. It assumes one steady pace for the whole distance, so treat every figure as arithmetic, not a forecast. For other everyday sums, see the free online calculators.
| Distance and time | Per km | Per mile | Speed |
|---|---|---|---|
| 5K in 25:00 | 5:00 | 8:03 | 12.00 km/h, 7.46 mph |
| 5 miles in 50:25 | 6:16 | 10:05 | 9.58 km/h, 5.95 mph |
| 10K in 48:30 | 4:51 | 7:48 | 12.37 km/h, 7.69 mph |
| Half marathon in 1:45:00 | 4:59 | 8:01 | 12.06 km/h, 7.49 mph |
| Marathon in 4:00:00 | 5:41 | 9:09 | 10.55 km/h, 6.55 mph |
| Walk, 6 km in 1:12:00 | 12:00 | 19:19 | 5.00 km/h, 3.11 mph |
The first answer is already on screen. Change any number and the result, the splits and the tables update at once, with no Calculate button.
Choose Pace, Time or Distance. The field you are solving for disappears and becomes the big answer, so you only fill in the two you know.
Tap 1 mile, 5K, 10K, 10 mile, half marathon or marathon, or type any distance from 0.01 to 1,000 km in km, miles or metres.
Time goes in as hours, minutes and seconds, up to 99:59:59. Pace goes in as minutes and seconds per km or per mile, or as a speed in km/h or mph.
Open the split table, the pace in every unit, the times at this pace and the Riegel estimate, then copy the result or share a link with the same inputs.
Each row shows the formula and the same 5K in 25:00 worked by hand. The calculator uses whole seconds and exact distances, and rounds only the number it displays.
| Quantity | Formula | 5K in 25:00 |
|---|---|---|
| Pace per km | time in seconds ÷ distance in km |
1,500 ÷ 5 = 300 s = 5:00 |
| Pace per mile | pace per km × 1.609344 |
300 × 1.609344 = 482.8 s = 8:03 |
| Speed in km/h | 3,600 ÷ pace in seconds per km |
3,600 ÷ 300 = 12.00 km/h |
| Speed in mph | km/h ÷ 1.609344 |
12.00 ÷ 1.609344 = 7.46 mph |
| Finish time | pace × distance |
300 s per km × 5 km = 1,500 s |
| Distance | time ÷ pace |
1,500 s ÷ 300 s per km = 5 km |
| Distance | Exact value | Where it comes from |
|---|---|---|
| 1 mile | 1,609.344 m | The exact conversion factor printed in the NIST guide to SI units, appendix B.8. |
| Marathon | 42.195 km | Set by the International Amateur Athletic Federation (now World Athletics) in May 1921, from the length used at the 1908 London Olympics. |
| Half marathon | 21.0975 km | Half of the marathon distance. |
| 5K, 10K, 10 mile | 5 km, 10 km, 16.09344 km | Round numbers of kilometres, and 10 times the exact mile. |
Each row holds one even pace from start to finish. Times are rounded to the second. For any other pace or distance, type it into the calculator above.
| Per km | Per mile | km/h | mph | 5K | 10K | Half | Marathon |
|---|---|---|---|---|---|---|---|
| 3:30 | 5:38 | 17.14 | 10.65 | 17:30 | 35:00 | 1:13:50 | 2:27:41 |
| 4:00 | 6:26 | 15.00 | 9.32 | 20:00 | 40:00 | 1:24:23 | 2:48:47 |
| 4:30 | 7:15 | 13.33 | 8.28 | 22:30 | 45:00 | 1:34:56 | 3:09:53 |
| 5:00 | 8:03 | 12.00 | 7.46 | 25:00 | 50:00 | 1:45:29 | 3:30:59 |
| 5:30 | 8:51 | 10.91 | 6.78 | 27:30 | 55:00 | 1:56:02 | 3:52:04 |
| 6:00 | 9:39 | 10.00 | 6.21 | 30:00 | 1:00:00 | 2:06:35 | 4:13:10 |
| 6:30 | 10:28 | 9.23 | 5.74 | 32:30 | 1:05:00 | 2:17:08 | 4:34:16 |
| 7:00 | 11:16 | 8.57 | 5.33 | 35:00 | 1:10:00 | 2:27:41 | 4:55:22 |
| 7:30 | 12:04 | 8.00 | 4.97 | 37:30 | 1:15:00 | 2:38:14 | 5:16:28 |
| 8:00 | 12:52 | 7.50 | 4.66 | 40:00 | 1:20:00 | 2:48:47 | 5:37:34 |
| 9:00 | 14:29 | 6.67 | 4.14 | 45:00 | 1:30:00 | 3:09:53 | 6:19:45 |
| 10:00 | 16:06 | 6.00 | 3.73 | 50:00 | 1:40:00 | 3:30:59 | 7:01:57 |
An even pace is a simplification. A real race has hills, turns, weather and tiring legs, so the clock rarely matches a chart row exactly.
Many pace pages offer one direction, a handful of distances and a single number. These are the differences that matter when you plan a run or check a result.
| Feature | Basic pace calculator | This calculator |
|---|---|---|
| Solve for | Mode tabs and one result line | Pace, time or distance on one screen, with the other units shown beneath |
| Distances | A few presets, sometimes no custom distance | Six presets plus any distance from 0.01 to 1,000 km, in km, miles or metres |
| Pace and speed | One unit, or speed missing | Min per km, min per mile, km/h, mph, m/s and m/min together |
| Splits | Often none, or a fixed table | Cumulative and split times per km or mile, with optional negative or positive split |
| Race estimate | Rare, and often unlabelled | Riegel estimate marked as rough, with the source range stated |
| Working | Answer only | The substitution and the rounding rule, step by step |
| Sharing | Not always offered | Copy the result or share a link that opens with the same inputs |
Enter a distance and a finish time to see the pace per km and per mile, plus the clock time at every marker of a split table.
Switch the unit to km/h or mph to type a machine speed, and read it back as minutes per km or per mile. Incline and elevation are not part of the sum.
Try a negative or positive split to see how the same finish time spreads across the kilometres or miles of a run.
Solve for time from a walking pace or a cycling speed over a known route length, in km or miles.
Use the Riegel estimate as a rough guide, and the percentage calculator to see how far apart two paces or times are.
Once the duration is known, the calories burned calculator can estimate energy used for an activity and a time.
These notes explain the terms on the page in plain words. They describe how the numbers work, not what anyone should do.
General estimate only. This is arithmetic for educational use. It is not medical advice, a diagnosis or a training plan. Talk to a doctor or other qualified professional before you change your exercise or health care.
Pace is time per distance and speed is distance per time, so a faster runner has a smaller pace number and a bigger speed number. 5:00 per km and 12.00 km/h describe the same effort.
An even split holds one pace. A negative split makes the second half faster than the first and a positive split makes it slower. Here the percent is how much less or more time each km or mile takes in the second half, and the finish time stays the same.
One mile is 1.609344 km, so a pace per mile is the pace per km times 1.609344. A pace of 5:00 per km is 8:03 per mile.
A marathon is 42.195 km, about 26.22 miles. The figure was set by the International Amateur Athletic Federation in May 1921, and a half marathon is half of it.
Peter Riegel proposed T2 = T1 × (D2 ÷ D1)^1.06 in a 1977 magazine article and a 1981 American Scientist paper. A 25:00 5K gives 52:07 for 10K by this formula, a rough estimate and not a promise.
Distances are kept exactly and nothing is rounded until the last step. Times and paces round half up to the whole second, speeds to two decimals, so split times can differ by a second from one row to the next.
Every table assumes the pace is constant unless you choose a negative or positive split. It does not model hills, incline, wind, heat, heart rate or fatigue, and it gives no training advice.
The Riegel result is a rough estimate. The Peter Riegel page on Wikipedia says the 1981 paper covers efforts of 3.5 to 230 minutes and that some sites change the exponent for long distances, so outside that range expect more error.
Distances run from 0.01 to 1,000 km, times up to 99:59:59, paces from 0:30 to 99:59 and speeds from 0.1 to 120. The split table lists at most 200 rows. Energy needs are a separate question; the TDEE calculator covers that.
The mile length, the marathon distance and the Riegel formula come from the three pages opened for this page. The Riegel publication details (Runner’s World magazine, August 1977; American Scientist 69(3), 285 to 290, 1981) are as printed on the Wikipedia page, and the original article was not opened. The half marathon is half of the marathon, and every other figure is arithmetic shown in the working under the calculator.
Short answers about pace, speed, splits and the limits of this calculator.
Pace is the time taken to cover one unit of distance, shown as minutes and seconds per kilometre or per mile. A pace of 5:00 per km means each kilometre takes five minutes, and a smaller number is a faster pace.
Divide the total time by the distance. For a 5K in 25:00, 1,500 seconds divided by 5 km is 300 seconds, so the pace is 5:00 per km, which is 8:03 per mile. The calculator does the same sum with exact whole-number arithmetic and rounds only the number it shows.
Multiply the pace by the distance. At 5:00 per km, 10 km takes 10 times 300 seconds, which is 3,000 seconds or 50:00. Tap Time under Solve for, enter the distance and the pace, and the finish time appears.
Multiply the seconds per kilometre by 1.609344 to get seconds per mile, and divide by 1.609344 to go the other way. For example, 5:00 per km is 300 x 1.609344 = 482.8 seconds, shown as 8:03 per mile. The table called Pace and speed in every unit shows both.
Speed in km/h is 3,600 divided by the pace in seconds per kilometre, so 5:00 per km is 3,600 / 300 = 12.00 km/h. For mph, divide the km/h figure by 1.609344, which gives 7.46 mph.
A marathon is 42.195 km, so 4:00:00 divided by 42.195 km is 341.3 seconds per km, shown as 5:41 per km or 9:09 per mile when held evenly from start to finish. Real races rarely stay perfectly even.
A marathon is 42.195 km, about 26.22 miles. The International Amateur Athletic Federation, now World Athletics, set that length in May 1921. A half marathon is half of it, 21.0975 km, and the calculator uses both exact values for the Half and Marathon buttons.
A negative split means the second half of a run takes less time than the first, and a positive split means it takes more. Open Splits and cumulative times, choose Negative or Positive and a percent, and the table shows the time at every kilometre or mile while the finish time stays the same.
Peter Riegel proposed predicting a race time with T2 = T1 x (D2 / D1)^1.06, where T1 is a time over distance D1 and T2 is the predicted time over distance D2. It was described in a 1977 magazine article and a 1981 American Scientist paper. A 25:00 5K predicts 52:07 for 10K by this formula.
It is a rough estimate. The 1981 paper models efforts of about 3.5 to 230 minutes, and some sites change the 1.06 exponent because it can give seemingly unachievable predictions at longer distances. The formula ignores course, weather and training, so the page labels every prediction a rough estimate and stars times outside that range.
Distances run from 0.01 km to 1,000 km and times up to 99:59:59. Paces run from 0:30 to 99:59 per km or mile and speeds from 0.1 to 120. The split table lists at most 200 rows. Times and paces round half up to a whole second and speeds to two decimals. Outside the limits you get a message instead of a number.
No. The sums run in your browser and nothing is sent to a server. Your numbers appear in the page address only after you change a value or tap Share link, and only your choice of pace unit is remembered on your own device.