Free Engineering Tool

Speed & Velocity Converter

Convert between all common speed and velocity units instantly. Enter a value in any unit and see all conversions simultaneously.

m/s km/h mph ft/s knots Mach

All Conversions

Meters per Second

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Kilometers per Hour

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Miles per Hour

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Feet per Second

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Feet per Minute

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Knots

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Mach Number (20 °C air)

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Speed Unit Definitions

Speed is a scalar quantity measuring how fast an object moves. Velocity includes direction (vector). For unit conversion purposes, only the magnitude matters.

Unit	Symbol	Equals (m/s)	Notes
Meter per second	m/s	1.0000	SI base unit
Kilometer per hour	km/h	0.27778	1 km/h = 1000/3600 m/s
Mile per hour	mph	0.44704	1 mile = 1609.344 m
Foot per second	ft/s	0.30480	1 ft = 0.3048 m exactly
Foot per minute	ft/min	0.00508	Common for surface speed
Knot	kn	0.51444	1 nautical mile/hour
Mach (20 °C)	Ma	343.21	Speed of sound in air at 20 °C

Mach Number

The Mach number is the ratio of flow velocity to the local speed of sound. At 20 °C in dry air, the speed of sound is approximately 343.21 m/s (1235.6 km/h).

Ma = v / a, where a = 331.3 + 0.606 × T(°C) m/s

At sea level standard conditions (15 °C), a ≈ 340.3 m/s. This calculator uses 20 °C (a = 343.21 m/s).

Common Reference Speeds

Reference	m/s	km/h	mph
Walking speed	1.4	5.0	3.1
City driving	13.9	50	31.1
Highway driving	33.3	120	74.6
Speed of sound (20 °C)	343.2	1235.6	767.7
Bullet (rifle)	~900	~3240	~2013

Tip: For rotating machinery, surface speed (m/s or ft/min) = π × D × n / 60, where D is diameter in meters and n is RPM.

Speed & Velocity Converter | m/s km/h mph ft/s knots

Published by Nikolai Shelkovenko on February 15, 2026 February 15, 2026

All Conversions

Speed Unit Definitions

Mach Number

Common Reference Speeds