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Speed Calculator

Solve for speed, distance or time from the other two values, with instant conversion between km/h, mph, m/s and knots.

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Speed, Distance & Time Calculator
Pick what you want to solve for, then fill in the other two values
Enter values to calculate

Disclaimer. This calculator computes average speed, distance or time using simple constant-motion formulas — it does not account for acceleration, stops, or variable speed during a journey. Results are for estimation and planning purposes only. Read full disclaimer →

How Speed, Distance & Time Are Calculated

All three calculations are based on the same core relationship: Speed = Distance ÷ Time. This tool automatically rearranges the formula depending on which value you're solving for — Distance = Speed × Time when solving for distance, or Time = Distance ÷ Speed when solving for time.

Whatever units you enter in, the tool converts everything to metres per second internally, then displays results in km/h, mph, m/s and knots simultaneously so you never need a separate unit converter.

Worked Example

A car covers 150 km in 2 hours: Speed = 150 ÷ 2 = 75 km/h (46.6 mph, 20.8 m/s, 40.5 knots). If instead you know the car travels at 75 km/h for 2 hours, Distance = 75 × 2 = 150 km. And if you know it needs to cover 150km at 75km/h, Time = 150 ÷ 75 = 2 hours.

Frequently Asked Questions

Speed equals distance divided by time (Speed = Distance ÷ Time). This calculator can also rearrange the formula to solve for distance (Distance = Speed × Time) or time (Time = Distance ÷ Speed), depending on which two values you enter.
The calculator converts your input to metres per second internally, then displays the result in all four common speed units at once — so you get km/h, mph, m/s and knots simultaneously without needing a separate conversion step.
This calculator computes average speed — total distance divided by total time for a journey. Instantaneous speed (like a car's speedometer reading) is the speed at one specific moment, which can differ significantly if you sped up or slowed down during the trip.
A knot is one nautical mile per hour (1.15078 mph), used in aviation and maritime navigation because it's directly tied to degrees of latitude on the globe. A statute mile (used for mph) is a fixed land-distance unit unrelated to the Earth's geometry.
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