Speed Calculator
Solve the basic v = d / t equation for speed, distance or time — given any two of the three.
How to use the Speed Calculator
- Enter your inputs into the Speed Calculator above.
- Results update instantly as you type — no submit button needed.
- Adjust any value to see how the result changes in real time.
The speed equation
v = d / t · · · d = v × t · · · t = d / v
v is speed, d is distance, t is time. All three values must use consistent units (e.g., km/h, km and hours). The calculator handles unit conversions.
Worked example
Drove 300 km in 4 hours: average speed 75 km/h. To travel 200 miles at 60 mph: time = 200/60 ≈ 3.33 hours ≈ 3h 20min.
Frequently asked questions
What's average vs. instantaneous speed?
Average speed = total distance / total time, even if you stopped along the way. Instantaneous speed = speed at a specific moment (what your speedometer shows).
How do I convert km/h to mph?
Multiply by 0.6214. 100 km/h ≈ 62.14 mph. 60 mph ≈ 96.56 km/h.
What about acceleration?
Acceleration is the change in speed over time: a = Δv / Δt, measured in m/s² or mph/s. 0–60 mph times measure acceleration; lower time = higher acceleration.