Pick what you want to find — velocity, distance, or time — and enter the other two values in whatever units you have. Results come back converted to m/s, km/h, and mph.
How the velocity calculator works
Velocity, distance, and time are locked together by one relationship: velocity is distance covered per unit of time. Know any two and the third follows. The annoying part is never the algebra — it's the units, because distance arrives in miles or kilometers and time in minutes or hours. This calculator converts everything to meters and seconds internally, solves for the missing quantity, then presents the answer in the units you'd actually use, with speeds shown in m/s, km/h, and mph side by side.
The formula
v = d ÷ t ⇔ d = v × t ⇔ t = d ÷ v
v is average velocity, d the distance traveled, and t the elapsed time. Handy conversions: 1 m/s = 3.6 km/h ≈ 2.237 mph, and 1 mile = 1.609344 km.
Worked example
You drive 100 km in 1.5 hours. Average velocity:
v = 100 km ÷ 1.5 h = 66.67 km/h, which is 100,000 m ÷ 5,400 s ≈ 18.52 m/s ≈ 41.42 mph.
Flipping it around: at 12 km/h, covering 5 km takes t = 5 ÷ 12 h ≈ 0.4167 h = 25 minutes.
The average-speed trap
You cannot average speeds directly when the legs cover equal distances. Drive 100 km at 50 km/h and the next 100 km at 100 km/h — your average is not 75 km/h. The first leg takes 2 hours, the second only 1, so the trip is 200 km in 3 hours: 66.7 km/h. Slow legs eat disproportionate time, dragging the average toward them. To average speeds correctly, always go back to totals: total distance divided by total time — which is exactly what v = d ÷ t means.
Frequently asked questions
What is the formula for velocity?
Average velocity is distance divided by time: v = d ÷ t. The same relationship rearranges to solve for the other two quantities: distance = velocity × time, and time = distance ÷ velocity. This calculator handles all three, plus the unit conversions.
How do I convert m/s to km/h and mph?
Multiply m/s by 3.6 to get km/h (there are 3600 seconds in an hour and 1000 meters in a kilometer). Multiply m/s by about 2.237 to get mph. So 10 m/s = 36 km/h ≈ 22.4 mph.
What's the difference between speed and velocity?
Speed is how fast you're going; velocity is how fast and in what direction. Drive a full lap around a track at 100 km/h and your average speed is 100 km/h, but your average velocity is zero — you ended up where you started. For straight-line travel, which is what this calculator assumes, the two match.
How long does it take to travel a certain distance?
Divide the distance by your speed, keeping the units consistent: time = distance ÷ velocity. For example, 5 km at 12 km/h takes 5 ÷ 12 hours ≈ 0.417 h = 25 minutes. Pick "Solve for time" above and the calculator handles the unit juggling.
Does this calculator work for average or instantaneous velocity?
It computes average velocity — total distance divided by total time. Instantaneous velocity (what a speedometer shows at one moment) requires knowing the motion at every instant. If your speed varied during the trip, the result here is the constant speed that would have covered the same distance in the same time.