What are IATA and ICAO airport codes?

Aviation uses two separate systems to identify airports. IATA codes (International Air Transport Association) are three-letter identifiers used primarily in commercial aviation — you'll see them on boarding passes, booking platforms, and baggage tags. ICAO codes (International Civil Aviation Organization) are four-letter identifiers used in flight planning, air traffic control, and official aviation communications.

Every major airport has both codes, but they usually look quite different. For example, London Heathrow is LHR in IATA and EGLL in ICAO. The ICAO code encodes regional information in its prefix: the first letter indicates the world region, and the second often identifies the country.

Tool description

This tool converts between IATA and ICAO airport codes in both directions. Enter a three-letter IATA code to find the corresponding four-letter ICAO code, or enter a four-letter ICAO code to retrieve the IATA code. The conversion is instant and works for thousands of airports worldwide.

Examples

Input (IATA) Output (ICAO)
JFK KJFK
LHR EGLL
CDG LFPG
NRT RJAA
DXB OMDB
Input (ICAO) Output (IATA)
KJFK JFK
EGLL LHR
LFPG CDG
RJAA NRT
OMDB DXB

Features

  • Converts IATA codes (3-letter) to ICAO codes (4-letter) and vice versa
  • Covers thousands of airports worldwide from the airport-data-js database
  • Bidirectional — swap input and output with a single click
  • Validates code length before querying (3 chars for IATA, 4 for ICAO)
  • Clear error messages for unknown or invalid codes

How it works

IATA and ICAO codes are stored in a curated airport database. When you enter a code, the tool queries this database and returns the matching counterpart. ICAO codes follow a structured regional prefix system: K for the contiguous United States, EG for the United Kingdom, LF for France, RJ for Japan, and so on. This makes ICAO codes useful for understanding where an airport is geographically located just from its code.

Use cases

  • Flight planning: Pilots and dispatchers use ICAO codes for flight plans and NOTAMs; convert from the IATA code shown on a booking to the ICAO code required for filing
  • Aviation software: Systems like simulators, ATC tools, and navigation databases often require ICAO codes, while passenger-facing platforms use IATA
  • Data processing: Cross-referencing aviation datasets that use different code systems