Solve for speed, distance or time with multiple unit options
Speed, distance, and time are linked by the fundamental formula: speed = distance ÷ time. Knowing any two values lets you calculate the third. This calculator solves all three variants: given distance and time it returns average speed; given speed and time it returns distance covered; given speed and distance it returns the time required. It supports multiple unit systems — km/h, mph, m/s, knots — and converts between them automatically.
Average speed calculations are used constantly in everyday life: estimating travel times for a road trip, pacing yourself during a run, calculating fuel economy from trip logs, and verifying whether a delivery is on schedule. The same formula applies in physics, engineering (fluid flow, projectile motion) and sports analytics, making this one of the most broadly applicable calculators.
Speed is a scalar — it has magnitude only (how fast). Velocity is a vector — it has both magnitude and direction (how fast and which way). For everyday distance/time calculations, speed is what you need. Velocity matters when direction changes, such as in circular motion or navigation.
1 km/h = 0.621371 mph. Multiply km/h by 0.6214 to get mph, or divide mph by 0.6214 to get km/h. The calculator handles this conversion automatically.
A knot is 1 nautical mile per hour (1.852 km/h or 1.151 mph). It's the standard speed unit in maritime and aviation contexts because nautical miles are tied to degrees of latitude, making navigation calculations simpler.
Average speed as calculated here is total distance divided by total elapsed time. If you stop for 30 minutes during a 2-hour trip, those 30 minutes reduce your average speed. This is often called overall average speed, as opposed to moving average speed (excluding stopped time).
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