Speed Converter

Convert between all common speed units including meters per second, kilometers per hour, miles per hour, feet per second, knots, Mach number, and the speed of light.

Speed Converter 8 units

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Common Speed Conversions

All Speed Conversions

Browse all unit combinations — each page has a dedicated converter and conversion table.

Meters/second → Kilometers/hour Meters/second → Miles/hour Meters/second → Feet/second Meters/second → Knots Meters/second → Mach Meters/second → Cm/second Meters/second → Speed of Light Kilometers/hour → Meters/second Kilometers/hour → Miles/hour Kilometers/hour → Feet/second Kilometers/hour → Knots Kilometers/hour → Mach Kilometers/hour → Cm/second Kilometers/hour → Speed of Light Miles/hour → Meters/second Miles/hour → Kilometers/hour Miles/hour → Feet/second Miles/hour → Knots Miles/hour → Mach Miles/hour → Cm/second Miles/hour → Speed of Light Feet/second → Meters/second Feet/second → Kilometers/hour Feet/second → Miles/hour Feet/second → Knots Feet/second → Mach Feet/second → Cm/second Feet/second → Speed of Light Knots → Meters/second Knots → Kilometers/hour Knots → Miles/hour Knots → Feet/second Knots → Mach Knots → Cm/second Knots → Speed of Light Mach → Meters/second Mach → Kilometers/hour Mach → Miles/hour Mach → Feet/second Mach → Knots Mach → Cm/second Mach → Speed of Light Cm/second → Meters/second Cm/second → Kilometers/hour Cm/second → Miles/hour Cm/second → Feet/second Cm/second → Knots Cm/second → Mach Cm/second → Speed of Light Speed of Light → Meters/second Speed of Light → Kilometers/hour Speed of Light → Miles/hour Speed of Light → Feet/second Speed of Light → Knots Speed of Light → Mach Speed of Light → Cm/second

📐 How to Use

Select the unit you are converting from on the left and the unit you want on the right.
Put your speed in the value box; the result appears live in the second box and in the summary line underneath.
Tap the swap control between the two dropdowns to reverse the pair, then Copy to take the number with you.
Use the Common Speed Conversions grid to jump to pairs such as km/h to mph, or choose a link from All Speed Conversions for a page with its own converter and full conversion table.

❓ Frequently Asked Questions

QHow many mph is 100 km/h?

100 km/h is 62.1372 mph, since 1 km/h equals 0.62137169 mph. That makes the common European motorway limit of 120 km/h about 74.6 mph, and 50 km/h in town roughly 31 mph.

QWhat is 1 mph in km/h?

1 mph is 1.609343 km/h on this page, because a mile is 1609.344 meters. Converting the other way, 60 mph is 96.5606 km/h, which is why 60 mph and 100 km/h are often treated as loosely equivalent benchmarks.

QHow fast is one knot?

One knot is 1.851997 km/h, or 0.514444 meters per second. A knot is one nautical mile per hour, and the nautical mile is 1852 meters, one minute of latitude, which is what keeps it in use for shipping and aviation.

QWhy does 1 m/s show 3.599997 km/h instead of 3.6?

The kilometer per hour is stored as 0.277778 meters per second, a six-digit rounding of the exact 1/3.6. The error is about one part in a million, invisible for road speeds, so treat the last decimal place of any result as approximate.

ℹ️ About Speed Conversion

Speed pairs a length with a time, which is why so many units exist: kilometers per hour on most road signs, miles per hour in the United States and the United Kingdom, meters per second in physics, knots at sea and in the air, feet per second in ballistics. Mach is the odd one out. It is a ratio to the local speed of sound, which falls as air gets colder, so a Mach figure means little without an altitude attached. This page fixes it at 340.29 meters per second, sea level in a standard atmosphere.

Eight units are available, including the speed of light at 299,792,458 meters per second. Meters per second is the base that every conversion passes through. Each result is trimmed to four decimals above ten, six between one and ten, and eight below one. Nothing is sent anywhere; the conversion is JavaScript inside the page.

📏 8 Supported Units

Meter/second (m/s), Kilometer/hour (km/h), Mile/hour (mph), Foot/second (ft/s), Knot (kn), Mach (M), Centimeter/second (cm/s), Speed of Light (c).