Convert kilometres per hour to knots

One kilometre per hour is 0.539956803 knots. To convert any amount, multiply by 0.539956803. Going the other way, one knot is 1.852 kilometres per hour.

Multiply the kilometre per hour figure by 0.539956803. So kn = km/h × 0.539956803. For a quick mental estimate, dividing by about 1.85 gets you close enough for most everyday purposes.

One kilometre per hour is 100 km/h is a typical highway limit. Kilometres per hour is the speed-limit unit in every country except the US, the UK and a few small territories.

One knot is a cruising sailboat does about 6 knots. A knot is one nautical mile per hour. It is the standard for marine and air navigation because it maps directly onto latitude on a chart.

Because a nautical mile was defined as one minute of latitude, so it maps directly onto a chart — one degree of latitude is 60 nautical miles anywhere on Earth. That makes navigation arithmetic straightforward in a way statute miles or kilometres never could. It is now fixed at exactly 1,852 metres, which keeps that relationship near enough for practical purposes.

Yes. Since the 1959 international yard and pound agreement, the imperial and metric systems are related by exact definitions rather than measurements — the inch is exactly 25.4 mm and the pound exactly 0.45359237 kg. Everything derived from those, including this conversion, is therefore exact. Round at the end rather than partway through, since rounding km/h before converting introduces an error the conversion then multiplies.