How pace, time and distance fit together
Running pace is the time it takes to cover one unit of distance, usually a kilometre or a mile. Pace, time and distance are linked by one simple rule, so if you know any two you can find the third.
Time = pace × distance
Distance = time ÷ pace
To switch units, the calculator uses the exact international mile: 1 mile = 1.609344 km.
Speed (km/h) = 60 ÷ pace in minutes per km
Times are worked out in seconds and rounded to the nearest second only at the end, so a pace never shows as “4:60”.
Worked examples
Example 1: finding your pace. You ran a 10K in 55:00. That is 3,300 seconds ÷ 10 km = 330 seconds, so 5:30 per km. Per mile: 330 × 1.609344 = 531 seconds, or 8:51 per mile. Speed: 3,600 ÷ 330 = 10.9 km/h (6.8 mph).
Example 2: pace for a goal time. You want to run a marathon in 3 hours 45 minutes. 13,500 seconds ÷ 42.195 km = 320 seconds, so you need 5:20 per km or 8:35 per mile. The splits table shows the time you should see on your watch at each kilometre or mile, and you should pass halfway (21.1 km) in about 1:52:30.
Example 3: predicting other races. You ran a 5K in 25:00. Using Riegel’s formula, a well-trained 10K would take 25:00 × 2^1.06 = 52:07, a half marathon about 1:55:00 and a marathon about 3:59:47. Each longer race is a little slower per kilometre, because you cannot hold the same effort for longer.
Pace chart for common race distances
| Pace per km | Pace per mile | Speed | 5K | 10K | Half marathon | Marathon |
|---|---|---|---|---|---|---|
| 4:00 | 6:26 | 15.0 km/h | 20:00 | 40:00 | 1:24:23 | 2:48:47 |
| 4:30 | 7:15 | 13.3 km/h | 22:30 | 45:00 | 1:34:56 | 3:09:53 |
| 5:00 | 8:03 | 12.0 km/h | 25:00 | 50:00 | 1:45:29 | 3:30:59 |
| 5:30 | 8:51 | 10.9 km/h | 27:30 | 55:00 | 1:56:02 | 3:52:04 |
| 6:00 | 9:39 | 10.0 km/h | 30:00 | 1:00:00 | 2:06:35 | 4:13:10 |
| 6:30 | 10:28 | 9.2 km/h | 32:30 | 1:05:00 | 2:17:08 | 4:34:16 |
| 7:00 | 11:16 | 8.6 km/h | 35:00 | 1:10:00 | 2:27:41 | 4:55:22 |
| 8:00 | 12:52 | 7.5 km/h | 40:00 | 1:20:00 | 2:48:47 | 5:37:34 |
Race distances follow World Athletics rules: the marathon is 42.195 km (26.219 miles) and the half marathon 21.0975 km (13.109 miles).
The Riegel race predictor
In 1981 the engineer and runner Peter Riegel noticed that world-record times across many distances followed a simple curve. He published it in American Scientist:
T1 is your known time over distance D1, and T2 is the predicted time over D2. The exponent 1.06 means doubling the distance takes a bit more than double the time. The formula works best for efforts between about 3.5 minutes and a few hours, and only if you have trained properly for the longer distance. For first-time marathoners it is often optimistic, because the last 10 km depends heavily on endurance training and fuelling. Treat predictions as a target to test in training, not a promise.
Tips for using your pace
- Run most miles easy. Many coaches suggest that most weekly running should be at a conversational pace, often 60 to 90 seconds per km slower than 5K race pace.
- Start slower than goal pace. Going out too fast in the first few kilometres is the most common pacing mistake. Even or slightly faster second-half splits usually give the best result.
- Allow for the course. GPS watches often read long in races because you rarely run the measured shortest line. Aim a few seconds per km faster than the exact goal pace.
- Adjust for heat and hills. Hot weather and climbing both raise effort at the same pace, so judge by effort and heart rate on those days.
- Use speed on a treadmill. Treadmills show km/h or mph. A 6:00 per km pace is 10 km/h; an 8:00 per mile pace is 7.5 mph.
For general health, the CDC recommends adults get at least 150 minutes of moderate activity or 75 minutes of vigorous activity, such as running, each week, plus muscle-strengthening activity on two days.
Related calculators
Running burns a lot of energy, so check your daily needs with the calorie calculator and plan recovery with the sleep calculator. Adding strength work? The one rep max calculator sets your training weights. To convert other distances, use the length converter.