💨 Speed
Convert speed units free: kilometres per hour, miles per hour, metres per second and knots. Instant, accurate, no upload.
💨 Speed
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About the Speed Tool
Speed units vary by country and by domain. Road speeds are kilometres per hour almost everywhere except the United States and United Kingdom, physics uses metres per second, and aviation and marine navigation use knots — nautical miles per hour.
Converting matters practically: reading a speed limit sign abroad, interpreting a weather report’s wind speed, or checking whether an aircraft’s cruise speed is what you expected. This converter handles all four units instantly in your browser.
How to Use Speed
- Enter the speed value.
- Select the source unit.
- Select the target unit.
- Read the result immediately.
When to Use This Tool
- Interpreting road speed limits when driving in another country
- Converting wind speeds between weather report formats
- Translating physics calculations between m/s and km/h
- Understanding aviation or marine speeds quoted in knots
- Comparing vehicle performance figures across markets
Things Worth Knowing
- One knot equals 1.852 kilometres per hour exactly, since it is one nautical mile per hour.
- To convert m/s to km/h, multiply by 3.6.
- A rough mental rule: mph is about 60% of km/h.
Quick Facts
| Tool name | Speed |
| Category | Unit Converters |
| Price | Free — no account, no trial, no watermark |
| Where it runs | Entirely in your browser (client-side) |
| Files uploaded | None — your data never leaves your device |
| File size limit | None imposed; limited only by device memory |
| Works offline | Yes, once the page has loaded |
| Platforms | Windows, macOS, Linux, Android, iOS |
Frequently Asked Questions
How do I convert km/h to mph quickly?
Multiply by 0.62, or take roughly six-tenths. A 100 km/h limit is about 62 mph. For a quick estimate, halve it and add ten percent.
Why does aviation use knots?
Because a nautical mile corresponds to one minute of latitude, which makes navigation calculations on charts straightforward. Speed in knots relates directly to position change on a chart.
What is the conversion from m/s to km/h?
Multiply by 3.6. A metre per second is 3.6 kilometres per hour, since there are 3600 seconds in an hour and 1000 metres in a kilometre.
How fast is Mach 1?
Roughly 1235 km/h at sea level in standard conditions, but it varies with air temperature — Mach is a ratio to local sound speed, not a fixed value.