Speed Converter — Free Online Speed Unit Converter
Our free speed converter instantly converts between all major speed units. Use the speed converter to switch between miles per hour, kilometers per hour, meters per second, knots, Mach, and feet per second — no sign-up required. This speed converter uses verified conversion factors based on international SI standards. Learn more at Wikipedia on speed and velocity and the NIST unit conversion guide.
🚀 Speed Converter
Quick Reference Tables
Common speed values converted at a glance.
MPH → KMH
| Miles per Hour (mph) | Kilometers per Hour (km/h) |
|---|---|
| 0.5 mph | 0.80467136 km/h |
| 1 mph | 1.609343 km/h |
| 2 mph | 3.218685 km/h |
| 3 mph | 4.828028 km/h |
| 5 mph | 8.046714 km/h |
| 10 mph | 16.093427 km/h |
| 15 mph | 24.140141 km/h |
| 20 mph | 32.186854 km/h |
| 25 mph | 40.233568 km/h |
| 50 mph | 80.467136 km/h |
KMH → MPH
| Kilometers per Hour (km/h) | Miles per Hour (mph) |
|---|---|
| 0.5 km/h | 0.31068584 mph |
| 1 km/h | 0.62137169 mph |
| 2 km/h | 1.242743 mph |
| 3 km/h | 1.864115 mph |
| 5 km/h | 3.106858 mph |
| 10 km/h | 6.213717 mph |
| 15 km/h | 9.320575 mph |
| 20 km/h | 12.427434 mph |
| 25 km/h | 15.534292 mph |
| 50 km/h | 31.068584 mph |
Conversion Formulas
The exact math behind the most common speed conversions.
Understanding Speed Units
MPH vs KMH — Everyday Driving
The mile per hour (mph) is used for road speeds in the United States, United Kingdom, and a handful of other countries. The kilometre per hour (km/h) is the standard for the rest of the world and appears on road signs in over 160 countries.
A typical motorway speed limit of 70 mph = 112.65 km/h. A town speed limit of 30 mph = 48.28 km/h. Our MPH to KMH converter and KMH to MPH converter handle both directions instantly.
Meters per Second — The SI Standard
The meter per second (m/s) is the SI base unit of speed, used universally in science, physics, and engineering. It expresses how many metres an object travels per second. 1 m/s = 3.6 km/h = 2.237 mph.
Wind speed in meteorology, river flow rates, particle velocities in physics experiments, and projectile speeds in ballistics are all measured in m/s. ConvertNow converts m/s to and from all other speed units in a single step.
Knots — Navigation & Aviation
The knot (kn) is one nautical mile per hour and is the standard speed unit in maritime navigation and aviation worldwide. 1 knot = 1.852 km/h = 1.151 mph. Aircraft airspeed, ship speed, and wind speed in weather forecasts are all reported in knots.
A commercial airliner cruises at around 480–500 knots (890–926 km/h). A fast sailing yacht might reach 20 knots (37 km/h). Converting between knots and km/h or mph is essential for international navigation and flight planning.
Mach Number & the Speed of Light
The Mach number expresses speed as a multiple of the speed of sound (~340.29 m/s at sea level). Mach 1 = 1,236 km/h = 768 mph. Fighter jets and supersonic missiles travel at Mach 1 or above. Mach 2 = 2,470 km/h.
The speed of light (c) is the ultimate speed limit of the universe at exactly 299,792,458 m/s = 1,079,252,848 km/h. ConvertNow supports both Mach and the speed of light as reference units for scientific and aerospace contexts.
Frequently Asked Questions
Frequently Asked Questions
1 Miles per Hour (mph) equals 1.609343 Kilometers per Hours (km/h).
Multiply the value in Miles per Hours by 1.609343. For example, 10 Miles per Hours = 16.093427 Kilometers per Hours.
Yes. ConvertNow uses precise factors for all unit calculations. Currency conversions use live exchange rates updated regularly.
Yes — type into the right-hand field to reverse the conversion.