What this calculator does
Find out how fast you ran or walked, per mile or per kilometer. Give it a distance and a time, and it finds your pace. Or give it any two of pace, time and distance, and it finds the third. Pace is how long it takes you to cover one mile or one kilometer, in minutes and seconds. Runners like it because it matches a watch. At a 10:00 mile pace, each mile marker comes ten minutes after the last.
Pick a standard race (5K, 10K, half marathon or marathon), or type any distance in miles or kilometers. You'll get your pace in both units, plus your speed in mph and km/h for a treadmill. A table shows the finish times you'd get at that same pace, from 1,500 m up to the marathon.
Where it's used
Why this math matters outside the classroom:
- Race pace. Running 5 km in 25 minutes is a pace of 5 minutes per kilometer, which is a speed of 12 km/h.
- Goal times. A runner aiming for a 50-minute 10K needs 5:00 per kilometer, which is about 8:03 per mile.
- Distance from time. A runner who holds 5:30 per kilometer for 44 minutes covers 44 ÷ 5.5, which is 8 kilometers.
- Converting pace. Converting a 6:00 per mile pace to about 3:44 per kilometer uses the exact 1 mile = 1.609344 km.
- Walking events. Walkers training for a charity 10K estimate their finish time from the steady pace they hold on practice walks.
Grade level and standards: Grade 6; Common Core State Standards for Mathematics 6.RP.A.3.b, 6.RP.A.3.d. © Copyright 2010. National Governors Association Center for Best Practices and Council of Chief State School Officers. All rights reserved.
How to use it
- Choose what to solve for: pace, time or distance.
- Pick a race distance, or choose Enter a distance and type it in miles or kilometers. Enter time as hours, minutes and seconds. Enter pace as minutes and seconds per mile or per km.
- When solving for pace, choose whether to show it per mile or per kilometer. Both are always listed in the results.
- Read the answer, the pace in both units, the speed, and the race table underneath.
What the inputs mean
- Race distance
- Standard road-race distances: 5K = 5 km (3.11 mi), 10K = 10 km (6.21 mi), half marathon = 21.0975 km (13.11 mi), marathon = 42.195 km (26.22 mi).
- Distance
- How far you went. It's used when Race distance is set to Enter a distance. Decimals are fine, such as 3.1 miles or 21.0975 km.
- Time: hours
- Whole hours of the total time. Leave it at 0 for runs under an hour.
- Time: minutes
- Minutes on top of the whole hours, from 0 to 59.
- Time: seconds
- Seconds on top of the whole minutes, from 0 to just under 60. Decimals are allowed, for timed results.
- Show pace per
- Which unit the main pace answer uses when solving for pace. It doesn't change the math.
- Pace: seconds
- The seconds part of the pace, plus the unit: per mile or per kilometer.
Formula and method
pace = time ÷ distance time = pace × distance distance = time ÷ pace speed (km/h) = distance (km) ÷ time (hours) pace per mile = pace per km × 1.609344
These three formulas are really one idea, turned around. Pace is the time for each mile or kilometer. Speed is the distance you cover in an hour.
First, the calculator turns every time and pace into seconds, so the math is plain division and multiplication. For example, 1 h 5 min 30 s becomes 3,930 seconds. Then it turns the answer back into minutes and seconds, rounded to the nearest second.
If the distance and the pace use different units, it converts the distance using the exact length of a mile: 1 mile = 1.609344 km.
The race table multiplies your pace per kilometer by each race distance. The distances are 1.5 km, the mile (1.609344 km), and 3, 5, 10 and 15 km. Then come 10 miles, 21.0975 km for the half marathon and 42.195 km for the marathon.
Worked example
A runner covers 3.1 miles in 31 minutes and wants to know the pace.
- Time in seconds: 0 × 3,600 + 31 × 60 + 0 = 1,860 s.
- Pace: 1,860 s ÷ 3.1 mi = 600 s per mile, which is 10:00 per mile.
- Per kilometer: 600 ÷ 1.609344 = 372.8 s, shown as 6:13 per km.
- Speed: 3.1 mi ÷ 0.516667 h = 6 mph (about 9.66 km/h).
Result: The pace is 10:00 per mile (6:13 per km). If you held that pace over longer races, you'd run a 10K in 1:02:08, a half marathon in 2:11:06 and a marathon in 4:22:11.
Understanding the result
The race table assumes you keep exactly the same pace the whole way. Most runners slow down over longer races. So if you start from a short run, treat the marathon and half-marathon times as a best case.
Pace and speed tell you the same thing in two ways. A lower pace number means you're faster, but a higher speed number means you're faster. That's why the two can feel backward at first.
Assumptions and limitations
- Your pace stays the same over the whole distance.
- Race distances are the standard road distances: 5 km, 10 km, 21.0975 km and 42.195 km. A distance typed as 3.1 miles is a little shorter than a true 5K (3.107 miles).
- Times and paces are shown rounded to the nearest second.
- Hills, heat, wind, ground surface and tiredness aren't included. So your real race times will differ from the table.
- GPS watches often measure a race as a little longer than its official distance. That makes the pace they show a little faster than your pace over the official distance.
- The calculator doesn't predict race times from your fitness or training. It only uses the pace you enter.
Frequently asked questions
How do I convert pace per mile to pace per km?
Divide the pace per mile by 1.609344. For example, 8:00 per mile is 480 seconds, and 480 ÷ 1.609344 = 298.3 seconds. That's about 4:58 per km. The calculator shows both every time.
What is a good pace for a 5K?
There's no single good number. It depends on your age, experience, the course and the day. As a guide, a 10:00 mile pace gives a 5K in about 31 minutes, and an 8:00 pace about 25 minutes. The most useful comparison is with your own past runs on similar courses.
What treadmill speed matches my pace?
Divide 60 by your pace in minutes. A 10:00 mile pace is 60 ÷ 10 = 6.0 mph, and 8:00 per mile is 7.5 mph. The calculator shows the speed in mph and km/h for any pace.
What pace do I need for a 4-hour marathon?
Choose Pace, pick Marathon as the race distance and enter a time of 4 hours. The answer is about 9:09 per mile, or 5:41 per km. Many runners aim slightly faster than this to leave a margin.
What is the difference between pace and speed?
Pace is time per distance, such as minutes per km. Speed is distance per time, such as km per hour. Each is the other flipped upside down: 6:00 per km is 10 km/h.
Can I use this for walking or cycling?
Yes. The arithmetic is the same for any activity. Cyclists usually think in speed rather than pace, and the calculator shows both.
How this calculator is checked
Method: Definition of pace (time per distance) and speed; exact mile definition (1.609344 km); standard road-race distances. The calculation is covered by automated tests with known reference values and edge cases. Last updated 2026-10-18. Found a problem? Tell us.
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