Aviation Unit Converters
Instantly convert between the most common aviation units. Every converter includes formulas, reference tables, and real-world aviation context.
Why Unit Conversion Matters in Aviation
Aviation is a stubbornly mixed-unit world. Airspeed and wind are given in knots, altitude and elevation in feet, temperature in degrees Celsius, altimeter settings in inches of mercury in the United States but hectopascals almost everywhere else, and fuel in gallons in some aircraft and liters or kilograms in others. Moving between these units quickly and without error is a routine part of flight planning, and a mistake can have real consequences — the 1983 “Gimli Glider” ran out of fuel partly because of a pounds-to-kilograms conversion error. Each converter here works in both directions in real time and shows the exact factor it uses.
Choosing the right converter
Match the converter to the quantity you are working with. Use knots, mph, and kph for speed and wind; feet and meters for altitude and runway dimensions; and nautical, statute miles, and kilometers for distance. Reach for Celsius and Fahrenheit when reading temperatures, inHg and hPa for altimeter settings on foreign METARs, and gallons and liters together with pounds and kilograms when reconciling a fuel order or a weight-and-balance sheet.
Precision and rounding
Convert once, at full precision, and round only the final figure to the precision the task requires. Rounding an intermediate value and then feeding it into another calculation compounds the error — a problem that grows over a multi-leg fuel plan or a long conversion chain. For fuel and weight, where a few percent can matter for center of gravity or endurance, keep at least one extra significant figure until the last step, and remember that fuel converted by volume still has to be converted to weight using the correct fuel density.
International operations
Flying internationally — or simply reading a foreign chart or METAR — means switching reference systems constantly. Most of the world reports altimeter settings in hectopascals and visibility in meters, publishes some altitudes in meters, and fuels aircraft in liters. Being fluent with these converters lets you cross-check a controller’s QNH, interpret a metric transition altitude, and confirm that a liters fuel uplift matches the pounds or kilograms your performance planning assumed.
Common mistakes to avoid
Four errors account for most conversion mishaps. Confusing statute miles with nautical miles — they differ by about 15 percent — distorts distance and groundspeed. Mixing US and Imperial gallons, which are roughly 20 percent apart, throws off fuel quantity. Confusing inches of mercury with hectopascals produces a wildly wrong altimeter setting. And premature rounding quietly accumulates through a calculation. Reading the units on every number before you act on it prevents nearly all of these.
How to verify
Treat any converted figure that affects safety of flight as a value to be confirmed, not trusted blindly. Verify critical numbers against your aircraft’s documentation, official weather products, and published charts before flight. The exact conversion factors and definitions behind these tools are documented on our methodology and sources pages. For applied planning, pair these converters with the fuel planning and navigation calculators.