Speed Converter

Speed Converter

Convert between different speed and velocity units including meters per second, kilometers per hour, miles per hour, knots, and Mach.

Last updated: March 2026 | By Patchworkr Team

Convert Speed

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What is Speed Conversion?

Speed conversion is the process of converting velocity measurements from one unit to another. Speed represents how fast an object is moving, measured as distance traveled per unit of time.

Different regions and applications use different speed units. Kilometers per hour (km/h) and meters per second (m/s) are used in the metric system, miles per hour (mph) in the US, knots for maritime and aviation, and Mach for supersonic speeds.

Understanding speed conversions is essential for international travel, aviation, maritime navigation, scientific calculations, and comparing performance metrics across different measurement systems.

Common Speed Units

Meters per Second (m/s)

The SI unit of speed. Common in physics and scientific applications. 1 m/s = 3.6 km/h.

Kilometers per Hour (km/h)

Standard unit for road speed in most countries. Easy to relate to everyday distances.

Miles per Hour (mph)

Used primarily in the United States. 1 mile = 1.60934 kilometers.

Knots (kn)

Used in maritime and aviation. 1 knot = 1 nautical mile per hour = 1.852 km/h.

Mach Number

Ratio of speed to the speed of sound. Mach 1 ≈ 343 m/s at sea level (varies with temperature and altitude).

Feet per Second (ft/s)

Imperial unit used in engineering. 1 ft/s = 0.3048 m/s.

Conversion Examples

Example: Highway Speed (km/h to mph)

Given:
Speed: 100 km/h
Conversion:
1 km/h = 0.621371 mph
Calculation:
100 km/h × 0.621371 = 62.1371 mph
Result:
≈ 62.14 mph

Frequently Asked Questions

What's the difference between speed and velocity?

Speed is a scalar quantity (magnitude only), while velocity is a vector (magnitude and direction). This converter handles speed/velocity magnitude in different units.

Why do planes use knots instead of mph?

Nautical miles (and thus knots) relate directly to latitude/longitude coordinates on Earth, making navigation calculations simpler. 1 minute of latitude = 1 nautical mile.

What is Mach 1?

Mach 1 is the speed of sound, approximately 343 m/s (1,235 km/h or 767 mph) at sea level at 15°C. It varies with temperature and altitude.

How fast is the speed of light?

The speed of light in vacuum is exactly 299,792,458 m/s (approximately 300,000 km/s or 186,282 miles/s). Nothing can travel faster than light.

Why is Mach speed variable?

Mach number is the ratio of object speed to the local speed of sound. Since sound travels slower in colder, thinner air at high altitudes, the same Mach number represents different actual speeds.

What's a typical car highway speed?

In most countries, highway speeds range from 100-130 km/h (62-81 mph). In the US, it's typically 55-75 mph (88-121 km/h).

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