Pace Calculator
This calculator converts between the three ways of describing how fast you are moving: pace, which is time per kilometre and is how runners think; speed, which is distance per hour and is how cyclists and treadmills think; and finish time over a set distance, which is what actually matters on race day. Give it a distance and a time and it returns the pace and speed those imply, along with what the same effort would produce over the standard race distances. Pace is the more useful of the two for running because it is the number you can hold in your head and check against a watch at each kilometre marker. Speed is more useful on a bike or a treadmill, where the display is in kilometres per hour and you are matching a number rather than counting splits. The calculator also gives pace per mile, because a great deal of training material and many race results are still written in miles even here. One caution on the projections: predicting a marathon time from a 5 km time assumes you have done the training for the longer distance, and the further you extrapolate the less that assumption holds. The projected times use the Riegel formula, which is a reasonable rule of thumb rather than a promise.
Projected times use the Riegel formula with an exponent of 1.06. They assume you have trained for the longer distance, and become less reliable the further they extrapolate.
How it works
Total time in seconds is divided by the distance in kilometres to give pace in seconds per kilometre, which is then shown as minutes and seconds. Speed is the distance divided by the time in hours. Pace per mile is the pace per kilometre multiplied by 1.609344, the exact number of kilometres in a mile. The projected times use the Riegel formula: predicted time equals your time multiplied by the ratio of the new distance to your distance, raised to the power of 1.06. That exponent above 1 is what makes longer distances proportionally slower.
Worked example
Take the defaults: 10 kilometres in 50 minutes. That is 3,000 seconds over 10 km, so 300 seconds per kilometre, which is a pace of 5:00 per km. Speed is 10 km divided by 50/60 of an hour, which is 12.00 km/h. Pace per mile is 5 minutes x 1.609344, about 8 minutes 3 seconds. Projecting to the marathon, 42.195 divided by 10 is 4.2195, raised to the power 1.06 is about 4.60, times 50 minutes gives roughly 3 hours 50 minutes.
Related calculators
- Running Pace: pace and splits for a target race time.
- Bike Pace: the same calculation for cycling.
- TDEE: the energy all that training uses.
- BMR: the energy you burn at rest.