Free running pace calculator converts time and distance into pace per kilometer or mile, speed, and predicted 5K, 10K, half and full marathon times.
Pace is how long it takes you to cover one kilometer or one mile, usually shown as minutes per kilometer. It is the most practical number for planning runs and races, because it stays stable even when distance changes.
Enter the distance you ran or plan to run and the time it took (or the goal time). The calculator immediately shows your pace per kilometer and per mile plus your speed in km/h and mph.
It also predicts your finish times for standard races - 5K (3.1 mi), 10K (6.2 mi), half marathon (13.1 mi) and full marathon (26.2 mi) - using the Riegel formula, which applies a fatigue factor as distance increases. This is a useful reality check when choosing a race goal.
Pick your unit, enter the distance and time, and everything updates instantly.
Divide your total time by the distance. For example, 50 minutes for 10 km is 50 / 10 = 5:00 per kilometer. To get pace per mile, multiply the per-km pace by 1.609.
Pace is time per distance (min/km or min/mi); speed is distance per time (km/h or mph). They are reciprocals: 5:00/km equals 12.0 km/h. Runners usually think in pace, while treadmills and apps often show speed.
The Riegel formula is a well-known endurance model with a fatigue factor of 1.06. It is reasonably accurate for evenly trained runners on flat courses, but terrain, weather and training status can shift predicted times by several minutes.
It depends on fitness and age. Many beginners run a 10K in 60-70 minutes (6:00-7:00/km) and a 5K in 30-35 minutes. Start at a conversational effort and build distance before chasing pace.
Increase weekly mileage gradually, add one tempo or interval session, and include strength work. Consistent aerobic running over 8-12 weeks typically improves race times by 5-10%.
Yes. The pace, speed and time calculations work for walking and treadmill runs too. Race predictions assume continuous running, so they are less reliable for walking.