Which aviation units this converter uses
Pilots bounce between knots and miles per hour, nautical and statute miles, inches of mercury and hectopascals, and pounds and kilograms. This page uses the international legal definitions so a number you convert here matches a number you would get from a careful E6B or from the fuel planner and density altitude calculator.
- Speed and distance. 1 international nautical mile = 1,852 m exactly, so 1 knot = 1.852 km/h exactly. 1 statute mile = 1,609.344 m.
- Altitude. 1 foot = 0.3048 m exactly. Flight level is feet divided by 100 (FL350 = 35,000 ft) as a unit only.
- Pressure. 1 inHg = 33.863886666666667 hPa; 1 hPa = 1 millibar. ICAO standard sea-level pressure is 1013.25 hPa, or 29.92126 inHg.
- Mass and volume. 1 lb = 0.45359237 kg; 1 US gallon = 3.785411784 L; 1 imperial gallon = 4.54609 L.
- Temperature. °F = °C × 9/5 + 32; kelvin = °C + 273.15.
- Vertical speed. 1 ft/min = 0.00508 m/s exactly. 1 knot of vertical speed is about 101.3 ft/min.
Worked examples
- 100 kt = 185.2 km/h = 115.08 mph.
- 1 nm = 1.15078 statute miles = 1.852 km = 6,076.12 ft.
- 29.92 inHg, as a two-decimal altimeter setting, is 1,013.2 hPa on this page’s constant (the exact ICAO standard 1013.25 hPa is 29.92126 inHg — the same convention the density-altitude calculator uses).
- 15°C = 59°F = 288.15 K (ISA sea-level temperature).
- 500 fpm = 2.54 m/s.
How to use it
Type in any field. Only that group updates, so you can convert a cruise speed in one place and a fuel quantity in another without them interfering. For fuel weight from gallons (6.0 or 6.7 lb/gal), use the fuel planner.
Frequently asked questions
How many miles per hour is one knot?
One knot is one nautical mile per hour. Because an international nautical mile is 1,852 metres and a statute mile is 1,609.344 metres, 1 kt equals 1.852 km/h and about 1.15078 mph.
How do I convert inches of mercury to hectopascals?
This page uses 1 inHg = 33.863886666666667 hPa, the same constant as the density-altitude calculator, so 1013.25 hPa is 29.92126 inHg. Hectopascals and millibars are numerically equal.
How many pounds are in a kilogram, and how many litres are in a US gallon?
1 pound (avoirdupois) is 0.45359237 kg exactly. 1 US gallon is 3.785411784 litres exactly. Fuel planning often also needs 6.0 lb/gal for 100LL or 6.7 lb/gal for Jet-A — use the fuel planner for those.
Is a flight level just feet divided by 100?
Yes, as a unit conversion: FL350 is 35,000 feet. The actual altitude the airplane flies on a flight level also depends on the altimeter being set to 29.92 inHg / 1013.25 hPa, which this converter does not model.