Home › Health › Running Pace Calculator
Running Pace Calculator
Pace is the runner’s speedometer: minutes per mile or per kilometre. Enter any two of distance, time and pace to find the third, see your speed in mph and km/h, get a split table for race day, or predict a 10K, half marathon or marathon time from a recent 5K.
Race predictions use the Riegel formula, which fits most runners well between 5K and marathon but assumes equal fitness and similar conditions — it tends to be optimistic for a first marathon. Splits assume perfectly even pacing; in practice most runners fade slightly in the second half. These are estimates for training and planning, not medical advice.
How it works
Pace is time divided by distance. Pace per km = total time in seconds ÷ distance in km; pace per mile = pace per km × 1.609344. Speed = distance ÷ time (km/h or mph). Finish time = pace × distance, and distance = time ÷ pace. Race prediction (Riegel, 1977): T2 = T1 × (D2 ÷ D1)1.06 — a longer race takes proportionally a little more than the distance ratio, because you slow down. Worked example 1: a 5K in 25:00 is 1,500 seconds ÷ 5 km = 300 seconds per km = 5:00 per km, and 300 × 1.609344 = 483 seconds = 8:03 per mile; speed 5 km ÷ (25/60) h = 12.00 km/h (7.46 mph). Worked example 2: a marathon (42.195 km) in 4:00:00 is 14,400 ÷ 42.195 = 341 seconds = 5:41 per km, 9:09 per mile. Worked example 3: at 5:00 per km, a 10K takes 5:00 × 10 = 50:00. Worked example 4 (Riegel): a 25:00 5K predicts a marathon of 1,500 × (42.195 ÷ 5)1.06 = 1,500 × 9.59 = 14,387 seconds, about 3:59:47.
Frequently asked questions
What is a good running pace?
It depends on the distance and on you. A 5K in 30 minutes (6:00 per km, 9:39 per mile) is a solid recreational result; 25 minutes (5:00 per km, 8:03 per mile) is strong for a regular runner; under 20 minutes (4:00 per km, 6:26 per mile) is club-runner territory. For a marathon, 4 hours (5:41 per km, 9:09 per mile) is the classic first-timer goal, and 3 hours (4:16 per km, 6:52 per mile) is a Boston-qualifying pace for many age groups. Compare against your own past times, not against strangers.
How do I convert pace per mile to pace per kilometre?
Multiply the pace in seconds by 0.621371 (or divide by 1.609344). An 8:00 per mile pace is 480 seconds × 0.621371 = 298 seconds = 4:58 per kilometre. Going the other way, multiply pace per km by 1.609344: 5:00 per km is 300 × 1.609344 = 483 seconds = 8:03 per mile.
What is the Riegel formula?
A formula from exercise physiologist Peter Riegel (1977): your time for a new distance equals your known time multiplied by the distance ratio raised to 1.06. It is remarkably accurate between 5K and marathon for trained runners, but it assumes the same fitness and conditions, and it is optimistic for a first marathon, where the last 10K is usually slower than the formula allows.
How do I run even splits?
Divide your target time by the number of kilometres or miles and hit that pace at every marker — the calculator prints the split table for you. Most runners run the first kilometre too fast and pay for it later; aim to reach halfway a few seconds slower than target pace, then hold it. For a marathon, even or slightly negative splits (second half faster) beat the common pattern of a fast start and a slow finish.
How fast is a 5-minute kilometre in mph?
5:00 per km is 12 km/h, which is 7.46 mph. A 6:00 per km pace is 10 km/h (6.21 mph), a 4:00 per km pace is 15 km/h (9.32 mph), and an 8:00 per mile pace is 7.5 mph (12.07 km/h). Speed = 60 ÷ pace in minutes per unit, so 60 ÷ 5 = 12 km/h.