Free tool · Life Events
Speed Converter
Convert speed units online for free: mph, km/h, m/s, knots, and ft/s.
This free online speed converter instantly converts a speed between miles per hour (mph), kilometers per hour (km/h), meters per second (m/s), knots, and feet per second (ft/s), with no sign-up and no download required. Enter a speed in any of these units and see it converted across all of them at once. Useful for travel, aviation, sailing, or physics problems.
- Nothing leaves your device
- Runs entirely in your browser
- Free, no account needed
How to use Speed Converter
Two steps, and nothing to install.
Enter a speed
Type a speed in mph, km/h, m/s, knots, or ft/s.
See it converted instantly
The tool converts your speed across all five units at once, right in your browser.
More free tools
Free, private, and no sign-up on any of them.
How this works in your browser
Speed conversion is fixed-ratio arithmetic - 1 mph equals a known, constant number of km/h, m/s, knots, and ft/s - so this tool simply multiplies your entered value by each conversion factor the moment you type, entirely in your browser with plain JavaScript. There is no server call and nothing to wait on.
Speed Converter vs. typical online calculators
| Feature | Speed Converter (in-browser) | Typical online calculators |
|---|---|---|
| Where the maths runs | In your browser, on your device | Often posted to a server to compute |
| Your inputs are stored | Never - nothing is sent or saved | Frequently logged with your session |
| Works offline once loaded | Yes | No - needs a live connection |
| Ads inside the result area | None | Common on free calculators |
| Account required | No | Often, to save or export results |
| Usage limits | None - free, unlimited use | Sometimes capped per day |
Who uses Speed Converter
Travel abroad
Convert a car’s speedometer reading or a posted speed limit between mph and km/h when driving in a country that uses a different unit than you’re used to.
Aviation and marine navigation
Convert between knots and mph or km/h when working with flight plans, weather reports, or nautical charts.
Physics and schoolwork
Quickly convert between m/s and other units for a physics problem or lab report without doing the arithmetic by hand.
Frequently asked questions
What it can and cannot do, and what happens to your files.
Is this speed converter free?
Yes, this speed conversion calculator is completely free to use with no limits.
What is a knot?
A knot is one nautical mile per hour, commonly used in aviation and maritime navigation - it is slightly larger than a standard mph.
Which unit is most common for weather reports?
This varies by country: mph in the US, km/h in most of the rest of the world, and knots in aviation and marine contexts.
How precise are the conversions?
Conversions use standard, widely accepted conversion factors, shown to three decimal places for practical accuracy.
Is there a free online speed unit converter?
Yes, this converter is completely free with no sign-up, and converts between all five units - mph, km/h, m/s, knots, and ft/s - at once.
Convert speed units instantly - free.
Files never leave your device. No upload, no account, and free for unlimited use.
Also see: Unit Converter