Running Pace Calculator
Convert a finish time and distance into pace per mile and pace per kilometer.
Enter the distance you ran and how long it took. Pace is shown in both mi and km units.
How is this calculated?
Pace = total seconds / distance. 1 mile = 1.609344 km. Formatted as mm:ss per unit. Speed is reported as km/h and mph.
About this tool
A running pace calculator converts a finish time and a distance into pace per kilometre and per mile, the two figures every training plan and race goal is written in. It is the single most-used number in distance running because everything (long run pace, threshold pace, marathon goal pace) is expressed as a per-unit time.
The calculator also produces speed in km/h and mph for treadmill targets, and the inverse calculation (target finish time given a pace) is one short edit away. Most Garmin, Coros, and Apple Watch fields default to pace per km in metric markets and pace per mile in the US, so being able to flip between units lets you plan international races, follow training plans written in the other unit system, and pace alongside friends without rewriting your splits.
How it works
Pace is simple division: total time divided by total distance. The conversion between kilometre and mile units uses the exact factor 1 mile = 1.609344 km.
Pace per km = total seconds / distance in km Pace per mile = total seconds / distance in miles Speed = distance / time 1 mile = 1.609344 km Conversion = pace per mile = pace per km x 1.609344
- Total seconds = hours x 3600 + minutes x 60 + seconds.
- Distance = the actual measured run, not the planned one (GPS drift can be 1 to 3 percent).
- Pace format = minutes:seconds per km or per mile, the convention used on every race clock since the 1980s.
- Speed = km/h or mph, useful for treadmill targets and cyclist comparison.
Worked example
You run 5 km in 25 minutes flat. What is your pace and speed?
- Total seconds: 25 x 60 = 1500 seconds.
- Pace per km: 1500 / 5 = 300 seconds = 5:00 per km.
- Convert to miles: 5 km / 1.609344 = 3.107 miles.
- Pace per mile: 1500 / 3.107 = 483 seconds = 8:03 per mile.
- Speed: 5 km / (25/60 hours) = 12.0 km/h, or 7.46 mph.
Race pace targets reference table
Required pace to hit common goal finish times. Find your goal race and read across to see the per-km and per-mile pace you have to hold.
| Goal race | Distance | Finish time | Pace /km | Pace /mi |
|---|---|---|---|---|
| 5K sub-20 | 5.0 km | 20:00 | 4:00 | 6:26 |
| 5K sub-25 | 5.0 km | 25:00 | 5:00 | 8:03 |
| 5K sub-30 | 5.0 km | 30:00 | 6:00 | 9:39 |
| 10K sub-45 | 10.0 km | 45:00 | 4:30 | 7:14 |
| 10K sub-50 | 10.0 km | 50:00 | 5:00 | 8:03 |
| Half-marathon sub-1:45 | 21.0975 km | 1:45:00 | 4:58 | 8:00 |
| Half-marathon sub-2:00 | 21.0975 km | 2:00:00 | 5:41 | 9:09 |
| Marathon sub-3:30 | 42.195 km | 3:30:00 | 4:58 | 8:00 |
| Marathon sub-4:00 | 42.195 km | 4:00:00 | 5:41 | 9:09 |
| Marathon sub-5:00 | 42.195 km | 5:00:00 | 7:06 | 11:26 |
Common mistakes and limitations
- Starting too fast. The most common 5K mistake is going out 15 to 30 seconds per km faster than goal, then fading. Even or slight negative splits beat positive.
- Trusting GPS in cities or trees. Urban canyons and dense forest produce 2 to 5 percent distance error. Use a track or chip time for accuracy.
- Easy runs at race pace. Easy runs should be 60 to 90 seconds per km slower than 5K pace. Most amateurs train easy runs too hard.
- Ignoring elevation. Use heart rate or perceived effort, not pace, on hilly routes.
- Forgetting heat. Above 20 C, sustainable pace drops 5 to 15 seconds per km for every additional 5 C.
- Forgetting altitude. Above 1500 m elevation, oxygen partial pressure starts to dent VO2 max. Expect 8 to 12 seconds per km slower at 2000 m and 20+ seconds at 2500 m until you have spent 3 weeks acclimating.
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Frequently asked questions
What is a good running pace for a beginner?
A comfortable conversational pace for a new runner is roughly 7:00 to 8:00 per km (11:15 to 12:50 per mile). The talk test is the simplest gauge: if you can hold a sentence without gasping, the pace is sustainable. Beginners should spend most weekly mileage in this easy zone and add structured speed work only after building a 20 to 30 km per week base.
How do I convert a goal finish time into a target pace?
Divide goal time by race distance. For a sub-2-hour half marathon (21.0975 km), the math is 7200 seconds divided by 21.0975 km equals 341 seconds per km, or 5:41 per km (9:09 per mile). Holding that pace requires lactate-threshold fitness near it, so most plans alternate threshold runs at goal pace with longer easy runs.
What is the difference between pace and speed?
Pace is time per distance (5:00 per km), speed is distance per time (12 km/h). They are inverses. Runners use pace because most race goals are framed as 'go this fast for this long', while treadmills and cyclists use speed because it sets the belt directly. The calculator shows both for cross-reference.
Why are my GPS pace and treadmill pace different?
Treadmills measure belt speed exactly, but GPS pace drifts with satellite quality, tree cover, urban canyons, and tunnels. A real-world 5:00 per km might read 4:55 to 5:10 on a watch. For the most accurate outdoor pace, use a measured track or a chip-timed race; for indoor work, trust the treadmill console after calibrating against a known route.
How does Riegel's race prediction formula extend this calculator?
Pete Riegel's 1981 formula predicts your next race time from a recent one: T2 = T1 x (D2 / D1)^1.06. The 1.06 exponent assumes fatigue scales mildly with distance. A 25:00 5K predicts a 51:50 10K and a 1:54 half-marathon. Real-world drift above 21 km is closer to a 1.08 exponent because marathon fueling and pacing are harder than the formula assumes.
Sources
- Daniels, Jack (2013) Daniels' Running Formula, 3rd ed., Human Kinetics - VDOT pace tables and training-zone conversions.
- ACSM (2021) Guidelines for Exercise Testing and Prescription, 11th edition, Chapter on aerobic exercise prescription.
- Riegel, Pete (1981) Athletic Records and Human Endurance, American Scientist 69(3): 285 to 290 - the Riegel race-time prediction formula.
- USATF (2024) Course Measurement Procedures - the certification standard for road race distances.