Speed Distance Time Calculator
Enter two values and click Calculate to find the third.
Enter two values and click Calculate to find the third.
How Does the Formula Work?
This calculator links speed, distance and time. Choose the quantity you want, enter the other two, and it returns the answer together with the same trip expressed in every supported unit: km/h, mph and m/s for speed, kilometers, miles and meters for distance, and hours, minutes and seconds for time.
Distance = Speed × Time
Time = Distance ÷ Speed
1 mile = 1.609344 km exactly (5,280 ft × 0.3048 m)
1 m/s = 3.6 km/h | 1 km/h ≈ 0.6214 mph ≈ 0.2778 m/s
Example: 100 km ÷ 2 hours = 50 km/h = 31.07 mph = 13.89 m/s
The Speed-Distance-Time Triangle
Teachers often draw the relationship as a triangle with distance on top and speed and time side by side underneath. Cover the quantity you are looking for and the other two show the operation: covering distance leaves speed × time, covering speed leaves distance ÷ time, and covering time leaves distance ÷ speed. The link is linear. Over the same distance, twice the speed takes half the time, and at the same speed, twice the distance takes twice as long. The formulas assume a constant speed, so for a real journey the result is the average speed over the whole trip, and stops count only if you add them to the time.
Worked Examples
A 450 km drive at an average of 90 km/h takes 5 hours. A runner who covers 100 meters in 10.4 seconds averages 34.62 km/h. A marathon of 42.195 km at a steady 12 km/h, which is 5 minutes per kilometer, takes 3 hours 30 minutes 59 seconds. Each of these comes straight from the calculator: enter the same values and it returns the same numbers.
Units and Rounding
The mile used here is the international mile of 5,280 feet, and because a foot is 0.3048 m by definition, a mile is exactly 1.609344 km. Meters per second become kilometers per hour when multiplied by 3.6, since an hour has 3,600 seconds. So 60 mph is 96.56 km/h, 10 m/s is 36 km/h and 120 km/h is 74.56 mph. Every result is worked out from the exact values you typed and rounded once: speeds and distances to two decimals, times to the nearest second. A value too small to show at two decimals reads "< 0.01" instead of 0.
Tips & Recommendations
Enter the route distance and the average speed you expect to estimate the driving time; add stops separately.
42.195 km at 12 km/h (5 min/km) takes 3 hours 30 minutes 59 seconds. Solve for speed to find the pace a target time needs.
60 mph is 96.56 km/h and 10 m/s is 36 km/h. The results list every unit at once, so nothing has to be converted by hand.
With the same braking deceleration, braking distance grows with the square of speed: going 120 km/h instead of 100 km/h makes it 1.44 times as long.
Frequently Asked Questions
How do I calculate speed?
Speed = Distance ÷ Time. Enter distance and time, select 'Solve for Speed'.
How do I find travel time?
Time = Distance ÷ Speed. Enter distance and speed, select 'Solve for Time'.
How do I convert km/h to mph?
Multiply km/h by 0.6214. Or use this calculator. It shows all units automatically.
Does this account for stops?
No. This calculates based on constant speed. Add stop time separately for realistic travel estimates.
What units are supported?
Speed: km/h, mph, m/s. Distance: km, miles, meters. Time: hours, minutes, seconds.
Recent Calculations
No calculations yet