IATA vs. ICAO Airport Codes
Three-letter IATA codes
IATA codes are three letters such as LAX, JFK, and LHR. Airlines, booking systems, and baggage tags use them because they are short and easy to recognize.
IATA codes are assigned by the International Air Transport Association and are the codes most travelers encounter.
Four-letter ICAO codes
ICAO codes are four letters such as KLAX, KJFK, and EGLL. Air traffic control and flight planning systems use them because the first letter identifies the region and the remaining letters identify the airport.
A single airport normally has both an IATA code and an ICAO code, and they are not interchangeable.
Finding an airport code
Search the airport code lookup by IATA, ICAO, city, or airport name. Each airport page links to its country page, time zone, and other airports in the same country.
This reference currently publishes a curated set of major international airports from the OpenFlights dataset.