Speed Converter

Convert speed units free online -- km/h, mph, knots, m/s, and feet per second. Accurate standard conversion factors for travel, aviation, and marine navigation use.

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How to Use This Tool

Enter a speed valueThe number you want to convert

Choose from and to unitskm/h, mph, knots, m/s, or ft/s

See the converted resultUsing exact standard conversion factors

Different Fields, Different Conventional Units

Speed gets measured in whichever unit best suits its context -- km/h or mph for road travel depending on country, knots for aviation and marine navigation, and meters per second for scientific and physics contexts. This converter handles all five with exact standard conversion factors.

Why Knots Specifically Suit Navigation

A nautical mile is defined to correspond to one minute of latitude on a navigational chart, which makes knots (nautical miles per hour) directly useful for navigation calculations in a way that km/h or mph, tied to land-based distance units, don't provide as cleanly.

The Exact Mile-to-Kilometer Relationship

1 mph converts to exactly 1.609344 km/h, derived from the internationally standardized mile definition. This calculator uses that exact figure throughout, ensuring precise conversion regardless of which unit pairing you select.

Frequently Asked Questions

Knots (nautical miles per hour) relate directly to navigational charts based on latitude and longitude, where one nautical mile corresponds to one minute of latitude -- a relationship that makes knots more directly useful for navigation calculations than km/h or mph would be.

1 mph equals exactly 1.609344 km/h, derived from the exact international mile-to-kilometer definition, which this calculator uses precisely rather than a rounded approximation.

This follows each country's broader unit system convention -- countries using imperial units (notably the US, UK for some contexts) display road speeds in mph, while most countries using metric measure road speed in km/h.

Meters per second is the SI-derived unit for speed, built directly from the base meter and second units, which makes it the natural choice for physics and scientific calculations even though everyday speed limits and aviation use the other units instead.

Yes, a knot (about 1.15 mph) is meaningfully faster than a mph for the same numeric value, so confusing the two units in navigation or aviation contexts would produce a real, non-trivial error.