Length Conversion
This tool will help you convert between eight different metric and imperial lengths, easy to use.
Speed Converter
This free online speed conversion tool allows you to quickly and accurately convert a speed measurement into a range of commonly used metric, imperial, and nautical units. Whether you’re comparing vehicle speeds, analysing motion in physics, working with aviation or maritime data, or converting international speed limits, this calculator provides fast and reliable results.
With this speed calculator, you can convert between Metres per Second, Kilometres per Hour, Feet per Second, Miles per Hour, and Knots. Simply enter a value into any of the available input fields, and the calculator will instantly convert and display the equivalent speeds across all other supported units, removing the need for manual calculations.
Enter speed value
m/s
ft/s
km/h
mph
kn
Calculated in your browser as you type. Very small results can show as 0 when rounded to few decimal places.
How to use it
The speed conversion calculator is a handy webtool to use to convert from one speed to another.
- Enter a valueType a speed into any one of the fields. Any number is accepted, including the ‘e’ exponent such as 3e8.
- Read the resultsAll the other fields update automatically with the converted speeds.
- Copy a valueClick the clipboard button beside any field to copy it.
- Tidy the numbersUse Decimal places to round the results, or leave it on full precision.
Handy conversions
1 m/s
Is exactly 3.6 km/h, or about 2.237 mph.
1 mph
Is exactly 1.609344 km/h, so 60 mph is about 96.6 km/h.
1 knot
Is exactly 1.852 km/h, or about 1.151 mph.
Speed unit comparison table
| Unit name | Symbol | Description | Equals in metres per second |
|---|---|---|---|
| Metre per Second | m/s | Base SI unit of speed | 1 m/s |
| Kilometres per Hour | km/h | Common unit for road speeds | 0.277778 m/s |
| Feet per Second | ft/s | Imperial unit often used in engineering | 0.3048 m/s |
| Miles per Hour | mph | Commonly used for road speeds in the US and UK | 0.44704 m/s |
| Knots | kn | Nautical speed based on one nautical mile per hour | 0.514444 m/s |
Helpful notes
On the road
km/h is widely used for road speed limits around the world, while mph is primarily used in the United States and the United Kingdom.
Air and sea
Knots are standard in aviation and maritime navigation.
Science and engineering
m/s is commonly used in scientific and physics calculations, and ft/s appears frequently in engineering and technical contexts.
Frequently asked questions
How do I convert mph to km/h?
Multiply miles per hour by 1.609344 to get kilometres per hour. For a quick estimate, multiply by 1.6, so 50 mph is about 80 km/h.
How do I convert km/h to m/s?
Divide kilometres per hour by 3.6 to get metres per second. For example 90 km/h is 25 m/s.
What is a knot?
A knot is one nautical mile per hour. A nautical mile is exactly 1,852 metres, so one knot is exactly 1.852 km/h, or about 1.151 mph.
Why use feet per second?
It is common in engineering, ballistics and some sports, where distances are measured in feet and time in seconds.
Can I type very large or very small numbers?
Yes. Any number is accepted, including scientific notation such as 3e8 for the speed of light in metres per second.
Is anything sent to a server?
No. The conversion is calculated in your browser as you type.
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