06 · Reference · Unit converter
Aviation unit converter .
Bidirectional conversions across the families pilots actually touch: distance, altitude, speed, temperature, pressure, weight, volume, and fuel. Constants from the FAA Pilot/Controller Glossary and ICAO Annex 5.
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Section 01
Convert
Section 02
Unit notes for pilots
Aviation lives between two unit systems — the United States retains statute miles, knots,
pounds, gallons, and inches of mercury; most of the rest of the world uses kilometres, metres
per second, kilograms, litres, and hectopascals. The conversions here use the FAA standards: 1 NM = 1.151 SM = 1.852 km, 1 kt = 1.151 mph,
1 in Hg = 33.864 hPa. Fuel uses the standard density assumptions of 6.0 lb/gal
for 100LL avgas and 6.7 lb/gal for Jet A.
A few conversions every PPL student should commit to memory: 3 NM ≈ 5.5 km,
10,000 ft ≈ 3,000 m, 100 kt ≈ 115 mph,
32 °F = 0 °C, 29.92 in Hg = 1013 hPa. Everything else is fine to
look up.
Temperature is the one family where conversion is not just a multiplication: the offsets between scales (32° between F-zero and C-zero; 273.15° between C-zero and absolute zero) make the formula non-linear. The calculator handles it; do not use a pure ratio for temperature.
Section 03
Common pitfalls
- 01Knots and miles-per-hour look similar but aren't — a 30 kt wind is 35 mph. Round-trip a knot value through MPH once and you lose 15%.
- 02Fuel pounds-to-gallons depends on the fuel. 100LL avgas is 6.0 lb/gal; Jet A is 6.7. Loading a Jet A tanker on a piston single using the avgas ratio is the wrong amount of fuel.
- 03Hectopascals and millibars are the same unit, but pressure-altitude formulas tabulated against in Hg use the 29.92 datum, not 1013.25 hPa. Don't substitute one for the other in a chart.
- 04Flight levels are pressure altitudes, not altitudes. FL180 is 18,000 ft only on a standard-pressure day. The converter knows this; you should too.
- 05Temperature conversions are non-linear because of the offset between scales. Doubling Celsius does not double Fahrenheit.
Download
Free on the App Store. iOS 18 and up.
The iOS app's Tools tab has the same unit converter alongside the operational calculators — useful when you're filing a flight plan in a country that wants metres while your GPS is set to feet.