🚗 Speed, Distance & Time Calculator
Enter any two of speed, distance and time, and the calculator works out the third.
Travel time
5h 0m
5 hours
The identity is distance = average speed × time. Give any two and the third follows: time = distance ÷ speed, speed = distance ÷ time. Keep units consistent (km with km/h, or miles with mph). This uses steady average speed, so real journeys with stops and traffic take longer. 🔒 In your browser.
How the speed, distance & time calculator works
Travel maths rests on one identity: distance = average speed × time. Rearranged, time = distance ÷ speed and speed = distance ÷ time. Pick which quantity to solve for, enter the other two, and the tool returns the answer, travel time is also shown in hours and minutes. Keep the units consistent (kilometres with km/h, or miles with mph); the toggle sets both together. Worked example: to solve for speed, a 240 km drive that took 3 hours 20 minutes (3.333 hours) averages 240 ÷ 3.333 ≈ 72 km/h. To solve for distance, 50 mph held for 2.5 hours covers 50 × 2.5 = 125 miles. The one thing that trips people up is entering time as a decimal, 90 minutes is 1.5 hours, not 1.30.
This assumes a constant average speed, so real journeys, with traffic, stops, junctions and speed limits, usually take longer than the ideal time. For a rough road-trip estimate, use a realistic average well below your top cruising speed, and add time for breaks.
Frequently asked questions
How do I calculate travel time?
Divide the distance by your average speed: time = distance ÷ speed. 300 km at 60 km/h takes 5 hours. The calculator also breaks the answer into hours and minutes.
How do I calculate average speed?
Divide the distance by the time taken: speed = distance ÷ time. Covering 150 miles in 3 hours is an average of 50 mph. Note this is average speed, including any slow sections, not your top speed.
How do I calculate distance from speed and time?
Multiply them: distance = speed × time. Two hours at 80 km/h covers 160 km. Make sure the speed and time units match (km/h with hours, mph with hours).
Why does my real journey take longer?
The formula uses a steady average speed, but real trips include acceleration, braking, traffic, junctions, rest stops and varying limits. Use a conservative average speed and add buffer time for a realistic arrival estimate.
What units should I use?
Keep them consistent: kilometres with km/h, or miles with mph, and time in hours (use decimals, 1.5 for an hour and a half). The km/mi toggle sets the distance and speed units together so they always match.
How do I enter minutes as a decimal?
Divide the minutes by 60 and add them to the hours: 30 minutes is 30 ÷ 60 = 0.5, so 2 hours 30 minutes is 2.5. Common values are 15 min = 0.25, 20 min = 0.333, 45 min = 0.75. Using 2.30 for two-and-a-half hours is the most common mistake.
What is the difference between average and instantaneous speed?
Average speed is the total distance divided by the total time, including every stop and slow section, and it is what this calculator uses. Instantaneous speed is what the speedometer shows at one moment. A trip can average 60 km/h while briefly touching 120, which is why the average is always lower than your cruising speed.