Kilometres and miles, side by side
Fill in two of distance, time and pace, and get the third, with your speed and finish times for the big race distances.
Your pace per kilometre
5:30/km
8:51 per mile
Choose what to work out, then fill in the other two boxes. Pace is time per kilometre or per mile: change the unit beside the box and everything else follows. The result shows pace both ways, your speed in km/h and mph, and how long 5K, 10K, a half marathon and a marathon take at that pace.
Finish times assume you hold the pace from start to finish. To plan a race kilometre by kilometre, or to run the second half faster, use the split calculator.
Predict it, split it, fuel it, log it.
A recent race becomes predicted times from the mile to the marathon, with Riegel’s formula and its limits.
Even or negative splits per km or mile that add up exactly, and a wrist band to print.
km/h and mph to pace per km and per mile, and back, with a table of common speeds.
Carbohydrate per hour for your finish time, a gel or drink schedule, and a fluid check.
Runs saved on your device, weekly totals in km and miles, and CSV export and import.
Two free services for the online side of running.
Training-plan downloads and running apps often want an email address first, then keep writing. CleanTempMail gives you a free temporary inbox straight away: no sign-up, a random or custom address on hundreds of domains, and messages deleted automatically after 3 days. Keep your real address for race entries, which send your bib number and start details.
Get a temporary inboxSpotted a race entry or running shoes at a surprising price on a site you have never heard of? WebTraceCheck’s free DNS and domain lookup shows how long a site’s domain has existed, and its disposable cloud browser opens unfamiliar links on an isolated desktop that is deleted after each session. Nothing to install, with free time every day.
Try WebTraceCheckDivide your time by the distance. 55 minutes for 10 km is 5.5 minutes per kilometre, which is 5:30 per km. For pace per mile, multiply by 1.609344: 8:51 per mile.
A half marathon is 21.0975 km (13.11 miles) and a marathon is 42.195 km (26.22 miles), the distances World Athletics uses. The race buttons above fill them in for you.
2:00:00 for 21.0975 km is 5:41 per km, or 9:09 per mile, at an even pace. The split calculator turns that into a split for every kilometre and a pace band you can print.
Pace is time per distance, such as 5:30 per km; speed is distance per time, such as 10.91 km/h (6.78 mph). They describe the same running, upside down. Treadmills show speed, so the treadmill converter switches between the two.