Speed Calculator
Calculate Speed, Distance, or Time
Result
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How to Use This Speed Calculator
Road trip planning hits the same wall: you know two of three numbers—distance, time, or speed—but rearranging v = d/t with mixed units trips people up. Pick what to solve for, enter the other two values with their units, and get results in m/s, km/h, and mph simultaneously.
- Select Find. Choose Speed (v), Distance (d), or Time (t). The unknown field hides.
- Enter Distance (d). When visible, type distance and pick Kilometers, Miles, or Meters.
- Enter Time (t). When visible, type time and select Hours, Minutes, or Seconds.
- Enter Speed (v). When visible, type speed and choose km/h, mph, or m/s.
- Press Calculate. Review the Result shown in multiple speed or time/distance units as applicable.
For broader unit work beyond motion problems, use the Conversion Calculator. For vehicle fuel efficiency after your trip, try the Gas Mileage Calculator or Fuel Cost Calculator.
Speed Calculator Formulas and Practical Applications
The classic relationship between speed, distance, and time assumes constant average velocity over the whole trip.
v = d / t
d = v × t
t = d / v
Example: a 300 km drive at 100 km/h takes t = 300/100 = 3 hours. A runner covering 400 m in 50 s has v = 400/50 = 8 m/s (about 28.8 km/h or 17.9 mph).
Standard Units and Conversion Tables
- 1 m/s = 3.6 km/h = 2.237 mph
- 1 km/h ≈ 0.278 m/s
- 1 mph ≈ 1.609 km/h = 0.447 m/s
- 1 mile = 1.609 km = 1,609 m
Frequently Asked Questions
Can I mix units like miles and minutes?
Yes. Select the appropriate unit for each input—the calculator converts to a consistent internal base (meters and seconds) before applying the formula, then shows results in common speed units.
Does this account for acceleration?
No. This tool assumes constant average speed over the entire distance. Stop-and-go traffic, speeding up, and slowing down require different kinematics equations.
Why do I get an error when solving for time?
Speed must be greater than zero when calculating time (t = d/v). Enter a positive speed value.
Which speed units appear in the result?
Results display simultaneously in m/s, km/h, and mph after the internal conversion from meters and seconds.
What does the Find dropdown control?
Choose Speed, Distance, or Time under Find. The unknown field hides; enter the other two with their unit dropdowns and press Calculate.