Speed Calculator
Solve for speed, distance, or time — enter any two to find the third
Solve For
Unit System
Distance (km)
km
Time
h
m
s
Result
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—
Also—
Knots—
Speed, Distance & Time Formula
The relationship between speed, distance, and time is one of the most fundamental in physics: Speed = Distance ÷ Time, or rearranged: Distance = Speed × Time, and Time = Distance ÷ Speed. Given any two values, you can calculate the third.
This calculator handles the unit conversions automatically — enter your known values, choose what you want to solve for, and the result is shown in multiple units simultaneously.
lightbulb Example
Delhi to Agra (230 km) at 80 km/h average speed:
1Time = 230 ÷ 80 = 2.875 hours
2= 2 hours 52 minutes 30 seconds
3Same at 100 km/h: 2h 18m
✓ Speed limit matters for travel time planning
Speed Unit Conversions
- 1 km/h = 0.6214 mph = 0.2778 m/s = 0.5400 knots
- 1 mph = 1.6093 km/h = 0.4470 m/s = 0.8690 knots
- 1 m/s = 3.6 km/h = 2.237 mph = 1.944 knots
- 1 knot = 1.852 km/h = 1.151 mph = 0.5144 m/s
- Speed of sound: ~1,235 km/h (Mach 1) at sea level
- Speed of light: 299,792 km/s = 1.08 billion km/h
Key Terms
- Average Speed
- Total distance divided by total time. Different from instantaneous speed (speedometer reading). A 300 km trip taking 4 hours = 75 km/h average, even if you drove 100 km/h on highways and 30 km/h in city traffic.
- Knot
- Nautical unit of speed used in aviation and maritime. 1 knot = 1 nautical mile per hour = 1.852 km/h. Aircraft speeds are typically quoted in knots (e.g., cruising speed ~490 knots ≈ 907 km/h).
- Mach Number
- Speed relative to the speed of sound. Mach 1 ≈ 1,235 km/h at sea level. Aircraft breaking the sound barrier fly above Mach 1.