Give any two of speed, distance and time to find the third, then convert the result to the unit you need.
Choose what to find, and fill in the other two. Results update as you type. A blank time box counts as 0.
Convert a speed from one unit to another.
Speed is how far something travels in a given time: speed = distance ÷ time. Rearranged, distance = speed × time and time = distance ÷ speed. If a car goes 100 meters in 20 seconds, its speed is 5 meters per second. Give the calculator any two of the three and it works out the other one, converting the units for you.
The SI unit of speed is the meter per second. In daily life, road speeds are given in kilometers per hour or miles per hour, ships and aircraft use knots, and fast-moving things such as light are measured against the speed of light, which is 299,792,458 meters per second. The calculator shows the answer in a standard unit and in a few others, and the converter below handles the rest.
The result is an average speed over the whole trip. A real journey has stops and changes of pace, so your speed at any moment can be higher or lower. To find average speed for a trip with stops, divide the total distance by the total time, including the stops.
The unit conversions use exact definitions: 1 mile = 1,609.344 meters, 1 foot = 0.3048 meter, 1 yard = 0.9144 meter, 1 inch = 0.0254 meter, and 1 nautical mile = 1,852 meters. So 60 miles per hour is 26.8224 meters per second, or 96.56064 kilometers per hour.
Divide the distance by the time. A trip of 150 miles in 3 hours is an average speed of 50 miles per hour.
Multiply the speed by the time. At 60 miles per hour for 1.5 hours, you travel 90 miles.
Divide the distance by the speed. A 100 kilometer trip at 60 kilometers per hour takes 1 hour and 40 minutes.
Multiply miles per hour by 1.609344. Sixty miles per hour is 96.56 kilometers per hour.
A knot is one nautical mile per hour, which is exactly 1.852 kilometers per hour, or about 1.15 miles per hour.
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