Speed Converter

Convert between km/h, m/s, mph, knots, ft/s, Mach, and other speed units instantly, normalized to m/s for accurate comparison of vehicle, wind, and maritime speeds.

How to Use

  1. Enter the speed value

    Type the speed value you want to convert.

  2. Select the units

    Choose the source unit (e.g., km/h) and the target unit (e.g., mph).

  3. View the result

    Click Convert to see the converted speed value.

What is Speed Unit Conversion?

Speed is the distance traveled per unit of time, and depending on which distance and time units you use, it can be expressed as m/s, km/h, mph, knots, ft/s, Mach, and more. Even at the same pace, conventions differ between countries and fields, so conversion is often necessary.

Uses by Field

  • m/s: The SI base unit of speed in physics and engineering, also used in wind-speed forecasts.
  • km/h: The standard unit for road speed limits and car speedometers in Korea and Europe.
  • mph: The miles-per-hour unit used in the US and the UK.
  • knot (kn): A maritime and aviation speed unit based on one nautical mile (1.852 km).
  • Mach: A ratio relative to the speed of sound, used to express the speed of supersonic aircraft.

This converter first translates every input into m/s and then recalculates it into the target unit, so it delivers accurate results regardless of the unit combination.

Calculation Formula

Every unit is routed through the base unit m/s before being converted.

Result = Input × (factor of source unit) ÷ (factor of target unit)

Key conversion factors (m/s per unit): km/h = 0.277778, mph = 0.44704, knot = 0.514444, ft/s = 0.3048, Mach = 343, m/s = 1.

Example: 100 km/h to mph

  • Convert to m/s: 100 × 0.277778 = 27.7778 m/s
  • Convert to mph: 27.7778 ÷ 0.44704 ≈ 62.14 mph

Here, a conversion factor represents how many m/s a single unit of that measure corresponds to.

Frequently Asked Questions

How many m/s is 1 km/h?
1 km/h is about 0.2778 m/s. To convert km/h to m/s, divide by 3.6.
How many miles per hour is 100 km/h?
100 km/h is about 62.14 mph. Since 1 km is roughly 0.6214 miles, multiplying by 100 gives about 62.14 mph.
What is the difference between mph and km/h?
MPH (Miles Per Hour) measures miles per hour, while km/h measures kilometers per hour. 1 mph is about 1.609 km/h. The US and UK use mph as standard, whereas Korea and Europe use km/h.
What is a knot?
A knot is a speed unit used in navigation and aviation, equal to traveling one nautical mile (about 1.852 km) per hour. 1 knot is about 1.852 km/h and is mainly used to indicate the speed of ships and aircraft.
What kind of unit is Mach?
Mach expresses speed relative to the speed of sound. Mach 1 corresponds to about 343 m/s (about 1,235 km/h) under standard atmospheric conditions at sea level. Since the speed of sound varies with temperature and altitude, this converter uses the standard value of 343 m/s.
Where is ft/s (feet per second) used?
ft/s measures the number of feet traveled per second and is used in US-style engineering, ballistics, and sports (such as pitch speed). 1 ft/s is exactly 0.3048 m/s, equal to about 1.097 km/h.
How do I convert wind speed from m/s to km/h?
Multiply the wind speed in m/s by 3.6 to get km/h. For example, a wind speed of 10 m/s reported by a weather service equals 36 km/h. Conversely, divide by 3.6 to convert km/h back to m/s.
How does this converter ensure accuracy?
It first converts every input into the SI base unit m/s and then recalculates it into the target unit. Results are rounded to six decimal places, making them precise enough for everyday use as well as for engineering reference.
2026 international standards

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