Knots to MPH Converter
Convert knots to miles per hour, km/h, m/s, ft/min and ft/s, or any of those back to knots, with the Mach number, Beaufort wind force, hurricane category, distance per hour and day, travel time and a conversion table.
How it works
1 knot = 1 NM/h = 1.150779 mph = 1.852 km/h (exact) = 0.514444 m/s = 101.27 ft/min · mph → knots: ÷ 1.150779 · km/h → knots: ÷ 1.852 · Mach = speed ÷ speed of sound, a = 20.05 × √(T in kelvin) m/s
A knot is one nautical mile per hour, the standard speed unit in aviation and marine navigation because it maps cleanly onto latitude: one nautical mile is one minute of arc. Converting to miles per hour multiplies by 1.15078, and to km/h by exactly 1.852, since the nautical mile is defined as 1,852 metres. Switch the unit next to the speed to go the other way, and the mph, km/h, m/s or ft/min you type is turned into knots. The feet-per-minute figure helps relate cruise speed to vertical rates on the same instrument scale. The Mach number divides the speed by the speed of sound at the air temperature you give (15 °C at sea level by default). For wind speeds, the page shows the WMO Beaufort force, and the Saffir-Simpson hurricane category from 64 knots up. Enter a distance under More options to get the travel time, and use the tables for quick knots ↔ mph ↔ km/h look-ups.
Worked example
100 knots × 1.15078 = 115.08 mph. The same speed is 100 × 1.852 = 185.2 km/h, or 100 × 0.514444 = 51.4 m/s, which is Mach 0.15 at 15 °C. As a wind it would be force 12, a category 3 hurricane. Covering 250 NM at 100 knots takes 2 h 30 min. Going the other way, 60 mph ÷ 1.15078 is 52.1 knots.
Sources: Knot (unit) — Wikipedia · NIST — nautical mile = 1,852 m · NOAA NHC — Saffir-Simpson Hurricane Wind Scale · NWS — Beaufort wind force scale
Frequently asked questions
Why do ships and aircraft use knots?
One nautical mile equals one minute of latitude, so speed in knots ties directly to position on a chart — one knot moves you one minute of arc per hour. That geometric link is why the unit persists in navigation despite the metric system elsewhere.
Is a knot the same as a nautical mile?
No. A nautical mile is a distance (1,852 m); a knot is a speed of one nautical mile per hour. Saying "knots per hour" is a common mistake — the "per hour" is already built into the unit.
How do I go the other way, mph to knots?
Choose mph in the unit list next to the speed, or divide by 1.15078 (multiply by 0.86898). So 115 mph is about 100 knots, and 60 mph is roughly 52 knots. The mph-to-knots table lists common values.
How fast is Mach 1 in knots?
It depends on the air temperature. At 15 °C (standard sea level) the speed of sound is 340.3 m/s, about 661 knots or 761 mph. At −56.5 °C, typical at airliner cruise height, it is about 573 knots. Set the temperature under More options.
How many knots is a gale or a hurricane?
On the Beaufort scale a gale (force 8) is 34–40 knots and hurricane force (12) starts at 64 knots. Hurricanes are then graded by the Saffir-Simpson scale: category 1 from 64 knots, 2 from 83, 3 from 96, 4 from 113 and 5 from 137 knots.
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This calculator is for educational purposes. Double-check important results before acting on them.