Speed Converter
Convert between m/s, km/h, mph, ft/s, and knots instantly.
About the Speed Converter
The Speed Converter turns any speed or velocity into another unit instantly — meters per second, kilometers per hour, miles per hour, feet per second, and knots. Type a number, pick the unit you have and the unit you want, and the answer appears immediately. All the math runs in your browser, so it's instant and works offline once the page has loaded.
Speed conversions come up constantly: reading a car's speedometer abroad, checking a wind or weather report, following a running or cycling pace, planning a flight or boat trip, or working through a physics problem. Different fields prefer different units — sailors and pilots use knots, scientists use meters per second, and most road signs use kilometers or miles per hour — so a quick, reliable converter saves time and prevents mistakes.
How to use
- Enter a value in the "From" box.
- Choose the unit you're converting from in the first dropdown.
- Choose the unit you want in the second dropdown — the result updates as you type.
- Use the ⇄ swap button to reverse the direction (for example, switch from "km/h → mph" to "mph → km/h") without re-entering anything.
Every conversion runs through meters per second as a common base using exact, internationally standardized factors — for instance, 1 km/h is exactly 1/3.6 m/s and 1 knot is exactly one nautical mile (1,852 meters) per hour. Results are shown with enough significant figures to stay precise without cluttering the display, and very large or very small numbers switch to scientific notation so they stay readable.
Common conversions
- 1 m/s = 3.6 km/h
- 1 km/h = 0.621371 mph
- 1 mph = 1.60934 km/h
- 1 knot = 1.852 km/h
- 1 m/s = 2.23694 mph
- 1 ft/s = 0.3048 m/s
Frequently asked questions
How accurate are the conversions?
Very accurate. Every unit is defined relative to meters per second using its exact international factor, so conversions are correct to eight significant figures — more than enough for driving, sports, navigation, and school. The only rounding is in how the result is displayed.
Does this work without an internet connection?
Once the page has loaded, yes. All the calculations happen locally in your browser with no server involved, so conversions keep working even if you go offline.
What is a knot and why is it used?
A knot is one nautical mile per hour, equal to exactly 1.852 km/h (about 1.15 mph). It's the standard speed unit in aviation and maritime navigation because a nautical mile corresponds to one minute of latitude, which lines up neatly with charts and navigation.
How do I convert km/h to mph quickly in my head?
Multiply km/h by roughly 0.62 to get mph, or divide by about 1.6. For example, 100 km/h is close to 62 mph. This tool does the exact math for you, but that rule of thumb is handy for a fast estimate on the road.
Can I convert very large or very small numbers?
Yes. The converter handles everything from a slow crawl of a few centimeters per second to the speed of a jet or beyond. Extremely large or small results are shown in scientific notation so they stay readable and precise.
Which units does it support?
Meters per second (m/s), kilometers per hour (km/h), miles per hour (mph), feet per second (ft/s), and knots — covering everyday driving, weather and wind reports, running and cycling pace, physics, and marine or aviation navigation.