What is a Speed, Distance & Time Calculator?
This calculator solves for any one of speed, distance, or time when the other two values are known. It is used for estimating travel time or calculating average speed.
How it's calculated
Speed = distance ÷ time / Distance = speed × time / Time = distance ÷ speed
To convert km/h to m/s, divide by 3.6.
Good to know
- The 3.6 conversion factor comes from simple unit math: 1 hour = 3,600 seconds, 1 km = 1,000 m, so 3600÷1000 = 3.6.
- Ships and aircraft use knots. 1 knot = 1 nautical mile/hour = 1.852 km/h. A nautical mile is defined as one minute of latitude, which made it convenient for navigation before GPS.
- The word knot comes from knots tied in a rope — sailors would throw a knotted line overboard and count how many knots passed in a fixed time to measure speed.
- Average speed is not the average of the two speeds. If you drive 60 km/h one way and 30 km/h back over the same distance, the average is not 45 but 40 km/h, because more time is spent at the slower speed.
- Average-speed enforcement zones measure your speed over a stretch of road, not at a single camera point, so slowing down only near a fixed camera does not help.
Frequently asked questions
Q. How many meters per second is 100 km/h?
About 27.8 m/s. Divide by 3.6.
Q. Why isn't round-trip average speed a simple average?
More time is spent in the slower leg, so the true average is weighted toward the slower speed. Total distance divided by total time gives the accurate figure.
Q. How many kilometers is 1 nautical mile?
1.852 km. It is defined as one minute of latitude on Earth.