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Running Pace Calculator

This running pace calculator solves for pace, finish time or distance in kilometers or miles. Use the 5K, 10K, half marathon and marathon presets and get an even-pace split for every kilometer or mile.

Solve forDistance unit

Distance

Elapsed seconds

Pace seconds per unit

Time and pace are entered in seconds. Split predictions assume constant pace and do not model terrain or fatigue.

Distance: 5.00 Kilometres
Pace: 0:06:00 per unit
Time: 0:30:00

Distance	Elapsed time
1	0:06:00
2	0:12:00
3	0:18:00
4	0:24:00
5	0:30:00

How pace, time and distance are calculated

Pacepace = elapsed seconds ÷ distance
Finish timetime = distance × pace seconds
Distancedistance = elapsed seconds ÷ pace seconds
Entering timesseconds = hours × 3600 + minutes × 60 + seconds
Per km → per milepace per mile = pace per km × 1.609344

Pick what to solve for, then the unit. Pace is per kilometer or per mile, matching the unit you choose. The race buttons fill in 5 km, 10 km, 21.0975 km or 42.195 km, converted to miles if Miles is selected. Pick the unit before pressing a preset. Results are shown as hours:minutes:seconds.

Time and pace are entered in seconds. Split predictions assume constant pace and do not model terrain or fatigue.

Worked example

A 10K finished in 55:00. Enter 3,300 seconds (55 × 60) with Solve for: Pace:

3,300 ÷ 10 = 330 seconds = 5:30 per km, or 8:51 per mile.

Kilometer	Elapsed time
1	5:30
2	11:00
3	16:30
4	22:00
5	27:30
6	33:00
7	38:30
8	44:00
9	49:30
10	55:00

These are even splits: every kilometer takes the same 5:30. On race day, write a few of them on your hand or a pace band to check you're not starting too fast.

Pace chart: finish times at an even pace

Pace per km	Per mile	5K	10K	Half	Marathon
4:00	6:26	20:00	40:00	1:24:23	2:48:47
4:30	7:15	22:30	45:00	1:34:56	3:09:53
5:00	8:03	25:00	50:00	1:45:29	3:30:59
5:30	8:51	27:30	55:00	1:56:02	3:52:04
6:00	9:39	30:00	1:00:00	2:06:35	4:13:10
6:30	10:28	32:30	1:05:00	2:17:08	4:34:16
7:00	11:16	35:00	1:10:00	2:27:41	4:55:22

Half marathon is 21.0975 km (13.1 miles) and marathon 42.195 km (26.2 miles). Real races are rarely run at a perfectly even pace, and GPS watches often measure a little long because runners don't take the shortest line around bends.

Predicting a longer race (not in this calculator)

Pace slows as distance grows, so a constant-pace calculation flatters you over longer races. Peter Riegel's 1981 formula is a common rough guide:

T2 = T1 × (D2 ÷ D1)^1.06

From a 30:00 5K it predicts 1:02:33 for 10K and 4:47:44 for a marathon. Holding the 5K pace of 6:00 per km would give 4:13:10. Predictions from short races often underestimate marathon times for runners without marathon training.

Using pace sensibly

Most easy and long runs are done well slower than race pace. If you can't speak in short sentences, you're likely going too hard.
For races, an even pace — or a slightly faster second half, called a negative split — is usually easier to sustain than starting fast and fading. Use the splits table as your target, and treat being a few seconds ahead at 5 km as a warning, not a bonus.
Hills, heat, humidity and wind all slow you down. Adjust targets by effort on those days rather than chasing the number.
If you're new to running, or have a heart condition or other health concern, check with a doctor before starting hard training. Stop if you feel chest pain, faintness or unusual breathlessness.

Sources: World Athletics marathon distance 42.195 km; international mile 1.609344 km; Riegel PS, Athletic records and human endurance, American Scientist 1981;69:285–90. Checked 15 October 2026.

Frequently asked questions

How do I calculate my running pace?+

Divide your time by the distance. A 5K in 30 minutes is 1,800 seconds ÷ 5 km = 360 seconds, or 6:00 per kilometer. Choose Solve for: Pace, enter the distance and your time in seconds, and the calculator does the division.

How do I enter a time like 25:30 or 1:45:00?+

Time and pace are entered in seconds: hours × 3600 + minutes × 60 + seconds. 25:30 is 1,530 seconds, 1:45:00 is 6,300 seconds, and a 5:30 per km pace is 330 seconds. Results are shown as hours:minutes:seconds.

How long will a marathon take at my pace?+

Choose Solve for: Time, press Marathon (42.195 km) and enter your pace in seconds. At 5:30 per km (330 seconds), the finish time is 3:52:04. That assumes you hold the same pace for the whole race.

How do I convert pace per kilometer to pace per mile?+

Multiply pace per kilometer by 1.609344, because a mile is 1.609344 km. A 6:00 per km pace is 9:39 per mile. In the calculator, switch the distance unit to Miles and enter the distance in miles to get pace per mile.

How far will I run in an hour at a given pace?+

Divide time by pace. Choose Solve for: Distance and enter 3,600 seconds with a pace of 300 seconds (5:00 per km): you cover 12.00 km.

What pace do I need for a sub-4-hour marathon or sub-2-hour half?+

Divide the goal time by the distance. Four hours over 42.195 km is 5:41 per km (9:09 per mile), and two hours over a 21.0975 km half marathon works out to the same 5:41 per km. The results are rounded to the second, so aim a few seconds faster to leave a margin.

What's the difference between pace and speed?+

Pace is time per distance (minutes per km or mile); speed is distance per hour, as shown on a treadmill. Convert with 3,600 ÷ pace in seconds = speed, or 3,600 ÷ speed = pace in seconds. A 5:00 per km pace is 12.00 km/h, and 10 km/h is 360 seconds, or 6:00 per km. Solving for distance over 3,600 seconds gives your speed directly.

How long are 5K, 10K, half marathon and marathon races in miles?+

A 5K is 3.11 miles, a 10K 6.21 miles, a half marathon (21.0975 km) 13.11 miles and a marathon (42.195 km) 26.22 miles. The race presets fill in the distance in whichever unit you've chosen.

What do the splits show?+

The table lists the elapsed time at every whole kilometer or mile, plus the finish, for an even pace. Use it as a pacing band or to check your watch mid-race. The table shows up to 100 rows.

Can it predict my marathon time from a 5K or 10K?+

No. The calculator holds pace constant and doesn't model fatigue, hills, heat or wind, so it can't convert a race result to a longer distance. Runners often use Riegel's formula for that (explained on this page), but any prediction is rough, especially from a short race to a marathon.

Is anything I enter saved or uploaded?+

No. All calculations run in your browser and nothing is stored or sent. Download summary saves a small text file with the result and splits to your own device.