Speed Calculator
Enter any two values — distance, time or speed — and the calculator solves the third. Handles mph, km/h, m/s and knots with instant conversion.
Frequently asked questions
How do I calculate speed?
Speed is distance divided by time: speed = distance ÷ time. For example, driving 240 miles in 4 hours gives 240 ÷ 4 = 60 mph. The calculator also flips the triangle: given any two of speed, distance and time, it finds the third.
How do I convert between mph and km/h?
Multiply mph by 1.60934 to get km/h, or divide km/h by 1.60934 to get mph. So 60 mph ≈ 96.6 km/h and 100 km/h ≈ 62.1 mph. A quick mental approximation: 1 mph ≈ 1.6 km/h, or 8 mph ≈ 13 km/h for round numbers.
What is a knot?
A knot is one nautical mile per hour (1.852 km/h), the standard speed unit in aviation and maritime navigation. 100 knots ≈ 115 mph ≈ 185 km/h. Nautical miles are based on the Earth’s latitude system, which is why they persist in navigation.