CALCULATOR
Pace Calculator
Running pace, speed and calories from any distance and time, plus predicted finish times for 5K, 10K, half and full marathon.
Your pace
–
Race predictions assume you can hold this pace for the full distance, which is optimistic for longer events. Most runners slow by 5 to 10 percent moving up a distance.
How pace, speed and race predictions work
Pace is simply time divided by distance, expressed as minutes per kilometre or per mile. Speed is the same relationship inverted, as distance per hour. Runners generally think in pace because it is the number you hold in your head during a run; cyclists think in speed.
The race predictions here assume you can sustain your current pace over the longer distance, which is deliberately optimistic. In reality most runners slow by roughly 5 to 10 percent when stepping up a distance, and the drop is larger from half marathon to marathon than from 5K to 10K. Treat the longer predictions as a ceiling rather than a forecast.
Calorie estimates use MET values scaled to your running speed and bodyweight. They are population averages and ignore terrain, wind, running economy and temperature.
The pace calculation
speed (km/h) = distance in km / (seconds / 3600)
per mile pace = per km pace x 1.609
Pace to speed conversion
| Pace per km | Pace per mile | Speed | 5K time | 10K time |
|---|---|---|---|---|
| 4:00 | 6:26 | 15.0 km/h | 20:00 | 40:00 |
| 4:30 | 7:14 | 13.3 km/h | 22:30 | 45:00 |
| 5:00 | 8:03 | 12.0 km/h | 25:00 | 50:00 |
| 5:30 | 8:51 | 10.9 km/h | 27:30 | 55:00 |
| 6:00 | 9:39 | 10.0 km/h | 30:00 | 1:00:00 |
| 6:30 | 10:28 | 9.2 km/h | 32:30 | 1:05:00 |
| 7:00 | 11:16 | 8.6 km/h | 35:00 | 1:10:00 |
Why longer races are slower per kilometre
Sustainable pace falls as distance rises because you draw on aerobic energy systems for longer, deplete glycogen, and accumulate muscular fatigue. A common rule of thumb is that doubling the distance costs roughly 5 to 7 percent in pace for trained runners, and more for beginners.
Realistic race predictions from a 10K
| 10K time | Half marathon | Marathon |
|---|---|---|
| 40:00 | 1:28 | 3:05 |
| 45:00 | 1:39 | 3:28 |
| 50:00 | 1:50 | 3:52 |
| 55:00 | 2:01 | 4:15 |
| 60:00 | 2:12 | 4:39 |
These use the widely cited Riegel exponent of 1.06, which assumes appropriate training for the longer distance. Someone who has never run beyond 15 km should not expect the marathon column to hold.
Training paces derived from race pace
| Session type | Relative to 10K pace | Purpose |
|---|---|---|
| Easy run | 60-90 seconds slower per km | Aerobic base, recovery |
| Long run | 45-75 seconds slower | Endurance |
| Tempo | 15-25 seconds slower | Lactate threshold |
| Intervals | 10-20 seconds faster | VO2 max |
- Most training volume should be easy. Running every session near race pace is the most common self-limiting error.
- Heat, hills, wind and altitude all slow pace at identical effort. Judge by effort on hard days.
- Track pace trends over months, not runs. Single-session variation is dominated by sleep, fuelling and conditions.
Frequently asked questions
What is a good running pace?
How do I convert pace between km and miles?
Why am I slower over longer distances?
Should I train at race pace?
Sources
- National Institutes of Health, Office of Dietary Supplements. Nutrient fact sheets. ods.od.nih.gov
- NHS. Nutrition and health guidance. nhs.uk
- US Departments of Agriculture and Health and Human Services. Dietary Guidelines for Americans, 2025-2030. dietaryguidelines.gov
More tools: all calculators · Full Plan · Recomp · Body fat · Macros · Cheapest whey per 20 g
General information, not medical advice. Consult a qualified professional before changing your diet, especially with a medical condition.