Speed, time and distance
Enter any two values and the third is calculated instantly: speed in km/h, mph or m/s, time in hours, minutes and seconds, distance in kilometers. With running pace per km and per mile.
The formula: speed = distance ÷ time
All three quantities are tied together by a single formula that can be rearranged three ways: speed = distance ÷ time, distance = speed × time, time = distance ÷ speed. To convert m/s to km/h you multiply by 3.6 (10 m/s is therefore 36 km/h), and one mile per hour equals 1.609 km/h, so a 60 mph highway speed limit is about 96.6 km/h. This tool handles all the conversions for you: just pick whichever unit you prefer from the menu.
Running pace per km and per mile
Runners don't think in km/h or mph, they think in minutes per kilometer or per mile. A classic example: 10 km in 50 minutes means a speed of 12 km/h, i.e. a pace of 5:00 per km (about 8:03 per mile). To run a half marathon (13.1 miles / 21.097 km) under 2 hours you need to hold at least 9:09 per mile (5:41 per km), and a marathon under 4 hours takes roughly the same steady pace over 26.2 miles. Enter your goal distance and target time and instantly see the pace to hold in your race or workout.
Nearby tools
The other running pages read and write pace and speed the same way: Running pace, Pace ⇄ speed, Training paces (VDOT), Race time prediction and Heart rate zones. On all of them 5:00 min/km and 12 km/h are the same pace, and a pace is always written in minutes and seconds, like 5:14.