Running pace from distance and time — pace per km/mile, speed and race predictions.
Example: 10 km in 50 minutes is a 5:00/km pace. Predictions assume you hold the same pace — in practice, longer races run a little slower per km.
How to use this tool
Pick a race preset or enter your own distance in km or miles.
Enter your finish time in hours, minutes and seconds — for example 50 minutes for a 10K.
Pace per km and per mile, speed in km/h and mph, and predicted times for 5K, 10K, half marathon and marathon at the same pace all appear together.
Copy your pace for a training plan, or share it with a running partner.
Formula & worked example
Worked example: 10 km in 50 minutes (3,000 seconds). Pace per km: 3,000 ÷ 10 = 300 seconds = 5:00/km. Pace per mile: 3,000 ÷ 6.2137 miles = 482.8 seconds = 8:03/mile. Speed: 10 km ÷ (50/60 hours) = 12.00 km/h = 7.46 mph. Predicted at the same pace: 5K 25:00, half marathon 1:45:29, marathon 3:30:59. Note the marathon prediction assumes the 5:00/km pace holds for all 42.195 km — most runners slow a little, so treat it as a best-case target.
Limitations — read this before you rely on it
Race predictions assume you hold exactly the same pace for the whole distance, which is optimistic for longer races — fatigue, hills, heat and fuelling all slow most runners, especially after 30 km in a marathon. Treat predictions as targets to train toward, not guarantees. Distances are course distances; GPS watches typically read slightly long, which makes watch pace look slightly slower than official race pace.
Frequently asked questions
Divide your time by the distance. 10 km in 50 minutes is 50 ÷ 10 = 5:00 per km. For miles: 10 km is 6.214 miles, so 50 ÷ 6.214 = 8:03 per mile. This running pace calculator does both conversions at once, plus speed in km/h and mph.
Pace is time per distance (minutes per km), speed is distance per time (km per hour) — they are reciprocals. A 5:00/km pace is 12 km/h, because 60 ÷ 5 = 12. Faster pace means a smaller number; faster speed means a bigger number. Runners talk pace, cyclists and drivers talk speed.
A marathon is 42.195 km (26.219 miles) and a half marathon is 21.0975 km (13.109 miles). At 5:00/km, a marathon takes 42.195 × 5 minutes = 210.98 minutes = 3:30:59, and a half takes 1:45:29. These predictions hold your pace constant; real marathons usually cost a few extra minutes in the last 10 km.
A 5K in 25 minutes (5:00/km) is a strong recreational time; 30 minutes (6:00/km) is a solid beginner-to-intermediate time; elite men run under 13 minutes and elite women under 15. What counts as 'good' depends on age, sex and training — compare against your own past times first.
Yes — enter miles and the calculator converts with 1 mile = 1.609344 km. A 10K is 6.214 miles, a marathon 26.219 miles. Pace per mile is always larger than pace per km because a mile is longer than a kilometre.