Running Pace Calculator
Turn a distance and a finish time into pace and speed, with Riegel equivalent times over the standard race distances.
Result
Enter distance to see the result.
https://calcgallery.com/fitness-training/running-pace-calculator/
How to use the Running Pace Calculator
- Enter the distance you ran, in kilometres, miles or metres.
- Enter the finish time as MM:SS or HH:MM:SS.
- Read your pace per kilometre or mile, and your speed.
- Look at the equivalent times for the standard race distances, and read what that model assumes.
How it is calculated
Pace and speed are two ways of expressing one relationship:
pace = elapsed time ÷ distancespeed = distance ÷ elapsed timeEverything is computed in metres and seconds and converted at the end. That matters more than it sounds: deriving a pace directly in minutes per mile, rounding it to the second and then building a split table on top accumulates error across the distance. Working in SI and converting once keeps the splits exact.
Metric readers get pace per kilometre and speed in kilometres per hour; imperial readers get pace per mile and miles per hour. The underlying run is identical.
Equivalent race times
Riegel’s model predicts a time at one distance from a performance at another:
T2 = T1 × (D2 ÷ D1)^1.06The exponent of 1.06 is the fatigue factor Riegel fitted to race results across distances in 1981. It is greater than one because pace slows as distance grows — a runner does not hold 5 km pace for a marathon.
The standard distances used are exactly as World Athletics defines them:
| Race | Distance |
|---|---|
| Mile | 1,609.344 m |
| 5 km | 5,000 m |
| 10 km | 10,000 m |
| Half marathon | 21,097.5 m |
| Marathon | 42,195 m |
What the model assumes. That you are comparably trained for both distances, running in comparable conditions on comparable terrain. Where that holds it is a good model. Where it does not, it is optimistic, and most markedly so at the marathon, where the gap between a runner’s 5 km fitness and their marathon-specific endurance is usually largest. A 20 minute 5 km predicts a 41:42 10 km, which is realistic for most runners. The same time predicts a 3:11 marathon, which is not, unless the marathon training has actually been done.
Practical tips
Predictions are most reliable between adjacent distances. A 5 km to a 10 km is a short extrapolation. A 5 km to a marathon is a long one.
Check the distance, not just the watch time. GPS drift of a few percent over a long run moves the pace more than most pacing decisions do.
Pace per kilometre and per mile are not interchangeable at a glance. A mile is over half a kilometre longer, so per-mile paces are always the larger number.
The marathon figure is exact for a reason. If you are working to a target time, the 195 metres matter.
Terrain and weather are not modelled. Hills, heat and wind all cost time, and nothing here accounts for any of them.
With your numbers
- Speed: 6.2 mi ÷ 0.833 hours = 7.44 mph
- Pace: 50:00 ÷ 6.2 mi = 08:04 per mi
Quick reference
Pace and speed are exact arithmetic. The equivalent times are a model that assumes comparable training and conditions.
| Example | Pace |
|---|---|
| 5 km in 25:00 | 05:00 |
| 5 km in 22:30 | 04:30 |
| 10 km in 50:00 | 05:00 |
| Half marathon in 1:45:00 | 04:59 |
| Marathon in 3:30:00 | 04:59 |
| 3 miles in 27:00 | 09:00 |
| 6.2 miles in 50:00 | 08:04 |
| 13.1 miles in 1:45:00 | 08:01 |
Where the numbers come from
The fixed figures this calculator relies on, and the published source each one was checked against. How the calculators are built and checked
5 sources
World Athletics Competition and Technical Rules (2026 edition), TR55 Road Races - Distances, p. 247: "Road Mile (1609.344m)".
Used for
- The mile, exactly 1609.344 m by the international yard and pound agreement.
World Athletics Competition and Technical Rules (2026 edition), TR55 Road Races - Distances, p. 247: 5km; CR32 lists the 5000m track record.
Used for
- The 5 km road and track distance.
World Athletics Competition and Technical Rules (2026 edition), TR55 Road Races - Distances, p. 247: 10km; CR32 lists the 10,000m track record.
Used for
- The 10 km road and track distance.
World Athletics Competition and Technical Rules (2026 edition), TR55 Road Races - Distances, p. 247. Derived: half the marathon TR55 gives (42.195 km); TR55 names the half marathon without stating its length.
Used for
- The half marathon, half of the marathon distance exactly.
World Athletics Competition and Technical Rules (2026 edition), TR55 Road Races - Distances, p. 247: "Marathon (42.195km)".
Used for
- The marathon, 42.195 km exactly.
Common questions about the Running Pace Calculator
- What is the difference between pace and speed?
- They are reciprocals. Pace is time per unit of distance, which is how runners usually think, because it maps onto what a watch shows each kilometre. Speed is distance per unit of time, which is how a treadmill is set. Five minutes per kilometre and twelve kilometres per hour are the same run; multiply seconds per kilometre by kilometres per hour and you always get 3,600.
- Why is my marathon prediction optimistic?
- Because Riegel assumes you are equally well trained for both distances, and almost nobody is. The exponent was fitted to race results from runners prepared for each distance they ran. Extrapolating a 5 km time to a marathon assumes marathon-specific endurance you may not have built, which is why the model is known to run fast at the marathon for undertrained runners.
- How do I convert between min/km and min/mile?
- A mile is 1.609344 kilometres, so a per-mile pace is the per-kilometre pace multiplied by that. Five minutes per kilometre is 8:02 per mile. The calculator does this by computing everything in metres and seconds and converting only at the end, which avoids the rounding drift you get from converting a pace that has already been rounded to the second.
- What is a good 5 km time?
- That is not a question with an answer. It depends on age, sex, training history, body composition, terrain, weather and what you are training for. Published age-graded tables exist for comparing performances across those factors and are a better tool than any single benchmark. This page reports what you ran.
- Why does the marathon distance have so many decimal places?
- Because it is defined as 42.195 kilometres exactly, not approximately. Rounding it to 42.2 changes a predicted three-and-a-half hour finish by several seconds, which is enough to matter to anyone chasing a time. The calculator reads the exact figure from its constants register.