ucUnitCloudInternational unit matrix

Mistake guide

Confusing knots and km/h

One knot is roughly one kilometre per hour.

01Assumption

One knot is roughly one kilometre per hour.

02Actually

One knot is one nautical mile per hour, exactly 1.852 km/h. So 30 knots is about 55.6 km/h, almost double.

03Why

The nautical mile derives from the angular measure of the Earth: one arc minute along a meridian. It remains standard in aviation and shipping because it relates directly to coordinates. Anyone who does not deal with navigation rarely knows the factor 1.852.

04Check

For a quick estimate multiply the knot figure by 1.85. Wind speeds at sea are also given in knots, while land weather reports use km/h — so the same number means a different speed.

Matching conversions

Knot to Kilometres per hourkn → km/hSpeedKilometres per hour to Knotkm/h → knSpeedMiles per hour to Kilometres per hourmph → km/hSpeedKilometres per hour to Miles per hourkm/h → mphSpeed

Matching tables

TableSpeed: km/h, m/s, mph and knots

Unit family: Speed

Sources

BIPM SI BrochureSI base units, prefixes and official SI context.NIST Guide to SI Appendix BNIST conversion-factor method and non-SI factors.
When not to use

Do not use as the sole basis for official, medical, safety-critical or contractual decisions.

Citation

Citation note: UnitCloud, mistake guide, sources reviewed: September 2026. Source basis: BIPM SI Brochure · NIST Guide to SI Appendix B.