Type a distance and a time, or tap a race. You’ll get pace per mile, pace per kilometer and your average speed.
A pace calculator turns a finish time into the number you’ll actually stare at on race morning. Nobody at mile 2 thinks, ah yes, 7.46 miles per hour. You’re thinking, wait, was that last mile 8:03 or did I just fall apart? So pick a race up there. Or type the length of that weird loop behind the high school, whatever it is. Add a time. Done. I tend to use the thing backward the night before a race, and then the splits go on the back of my hand in a Sharpie that never quite washes off by Monday.
How do I calculate my running pace?
Divide the time by the distance. Honestly that’s the whole secret, a pace calculator just spares you the long division on a sweaty phone. Take a 25-minute 5K. Since 5K is 3.107 miles, you get 25 ÷ 3.107 = 8.05 minutes, which your watch shows as 8:03 per mile. In kilometers it’s a lot less ugly, 5:00 flat, and you averaged around 7.46 mph.
Pace formula
Speed (mph) = distance in miles ÷ time in hours
1 mile = 1.609344 km
Finish times at common paces
| Pace per mile | 5K | 10K | Half marathon | Marathon |
|---|---|---|---|---|
| 7:00 | 21:45 | 43:30 | 1:31:46 | 3:03:32 |
| 8:00 | 24:51 | 49:43 | 1:44:53 | 3:29:45 |
| 9:00 | 27:58 | 55:55 | 1:57:59 | 3:55:58 |
| 10:00 | 31:04 | 1:02:08 | 2:11:06 | 4:22:11 |
| 12:00 | 37:17 | 1:14:34 | 2:37:19 | 5:14:38 |
Little nerdy detail: the race buttons don’t round. The half is 13.109 miles and the full is 26.219 (42.195 km), not the 13.1 and 26.2 from the bumper stickers. Over a marathon that tail is worth a couple of minutes, and you’ll feel them in your calves.
Treadmill speed to pace
| Treadmill (mph) | Pace per mile | Pace per km |
|---|---|---|
| 5.0 | 12:00 | 7:27 |
| 5.5 | 10:55 | 6:47 |
| 6.0 | 10:00 | 6:13 |
| 6.5 | 9:14 | 5:44 |
| 7.0 | 8:34 | 5:20 |
| 7.5 | 8:00 | 4:58 |
| 8.0 | 7:30 | 4:40 |
| 9.0 | 6:40 | 4:09 |
| 10.0 | 6:00 | 3:44 |
Treadmills talk speed. Your training plan talks pace. Of course they don’t agree, so somebody has to do math mid-run, and it’s you. The shortcut is 60 ÷ mph, which spits out minutes per mile. Some people bump the incline to 1% too, so the belt feels more like actual pavement.
My watch says I ran farther. Huh?
GPS watches tend to measure a race long. You don’t run the perfect tangents the course was measured on, and dodging around a water table adds up. So if your watch says 26.5 at the marathon finish? Your real pace per official mile was a touch slower than it bragged.
How to use the Pace Calculator
Pick a distance
Hit one of the race buttons, or type your own distance if you run some odd loop around the park, and say whether it’s miles or km.
Type your time
Finish time or goal time, hours, minutes, seconds. Whichever you’ve got.
Read your pace
Per mile, per km, plus average speed in mph and km/h. Copy it onto your hand if you’re old school.
How do I predict my race time from a shorter race?
The best-known method is the Riegel formula, published by engineer Peter Riegel in Runner’s World in 1977 and expanded in a 1981 American Scientist article. It assumes you slow down by a predictable amount as distance grows:
T2 = T1 × (D2 ÷ D1)^1.06
T1 is your known time over distance D1, and T2 is the predicted time for distance D2. Example: a 25:00 5K predicts a 10K of 25 × 2^1.06, which is about 52:07, and a half marathon of roughly 1:55.
Use it with some care:
- It works best for distances between about 3.5 minutes and 4 hours of running.
- Marathon predictions from a 5K are often too optimistic unless your weekly mileage supports the distance.
- Heat, hills and wind are not in the formula.
Once you have a target time, enter it here to get the per-mile or per-km pace. To train at the right effort for that pace, set your zones with the heart rate zone calculator.
How are race distances officially measured?
Road race courses are measured very differently from your watch. Under World Athletics and AIMS rules, a certified course is measured with the calibrated bicycle method: a Jones counter is fitted to the front wheel, the bike is calibrated on a steel-taped baseline, and the measurer rides the shortest possible route a runner could legally take, about 30 cm from curbs and cutting every tangent.
Measurers then add a short course prevention factor of 1.001, so a certified marathon is laid out at least 42 meters longer than 42.195 km. The goal is that no runner can cover less than the official distance.
- The marathon distance of 42.195 km (26.2188 miles) comes from the 1908 London Olympics and was fixed by the IAAF, now World Athletics, in 1921.
- A half marathon is 21.0975 km, or 13.1094 miles.
Since you will rarely run perfect tangents, your GPS will almost always show more than the official distance. Plan your pace on the official figure. To switch between kilometers and miles, use the km to miles converter.
Frequently asked questions
What is a good 5K pace?
Ask ten runners, get ten answers. I’d say if you’re a casual runner and you’re under 10:00 a mile, so finishing in about 31 minutes, you’re doing just fine. A 25-minute runner is cruising at around 8:03, for reference.
What pace do I need for a 4-hour marathon?
Roughly 9:09 a mile, 5:41 a km, and you hold it for all 26.2, which feels easy right up until mile 20 or so. Leave yourself a few seconds of slack for grabbing that paper cup of sports drink.
How do I turn pace per mile into pace per km?
Divide by 1.609. So an 8:00 mile turns into roughly 4:58 per km, give or take a second.
Treadmill says 6.5 mph. What pace is that?
60 ÷ 6.5 = 9.23 minutes. Or 9:14 a mile, in watch-speak.
What is a negative split?
Second half faster than the first. For a 4-hour marathon, maybe 2:01 out and 1:59 back. Hard to pull off. But going out too fast wrecks way more races than going out too slow.
Is pace the same as speed?
Nope, they’re flipped. Pace is time per distance, like minutes per mile. Speed is distance per time, like mph.
Can I use the pace calculator for walking or cycling?
Sure. Any distance, any time. Cyclists mostly think in mph though, so they’ll probably just glance at the speed box and leave.
Sources and further reading
Related tools
Last reviewed: October 2026