Mode S address lookup
AviationWhich country is an aircraft's transponder address from?
Type an aircraft's 24-bit Mode S or ADS-B address in hex, octal or binary to see the country block it belongs to.
What you enter stays on your device while you use this tool. Opening a shared link sends the settings in its address to HowToolbox to prepare the page.
The 24-bit ICAO address, such as 461F2B on a flight tracker
Address block belongs to
Finland
461F2B is in block 460000–467FFF · 32,768 addresses
The address in every notation
- Hexadecimal
- 461F2B
- Octal
- 21417453
- Binary
- 0100 0110 0001 1111 0010 1011
- Decimal
- 4,595,499
- Block
- 460000–467FFF
- Addresses in the block
- 32,768
- Fixed leading bits
- 010001100 + 15 free bits
The block shows which State gave out the address, not who owns or flies the aircraft. A State's register links the address to one aircraft.
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Address blocks by State (ICAO Annex 10, Table 9-1)
-
- Block (hex)
- 004000–0043FF
- Addresses
- 1,024
- Leading bits
- 00000000010000
-
- Block (hex)
- 006000–006FFF
- Addresses
- 4,096
- Leading bits
- 000000000110
-
- Block (hex)
- 008000–00FFFF
- Addresses
- 32,768
- Leading bits
- 000000001
-
- Block (hex)
- 010000–017FFF
- Addresses
- 32,768
- Leading bits
- 000000010
-
- Block (hex)
- 018000–01FFFF
- Addresses
- 32,768
- Leading bits
- 000000011
-
- Block (hex)
- 020000–027FFF
- Addresses
- 32,768
- Leading bits
- 000000100
-
- Block (hex)
- 028000–02FFFF
- Addresses
- 32,768
- Leading bits
- 000000101
-
- Block (hex)
- 030000–0303FF
- Addresses
- 1,024
- Leading bits
- 00000011000000
-
- Block (hex)
- 032000–032FFF
- Addresses
- 4,096
- Leading bits
- 000000110010
-
- Block (hex)
- 034000–034FFF
- Addresses
- 4,096
- Leading bits
- 000000110100
| Leading bits | |||
|---|---|---|---|
| 004000–0043FF | 1,024 | 00000000010000 | |
| 006000–006FFF | 4,096 | 000000000110 | |
| 008000–00FFFF | 32,768 | 000000001 | |
| 010000–017FFF | 32,768 | 000000010 | |
| 018000–01FFFF | 32,768 | 000000011 | |
| 020000–027FFF | 32,768 | 000000100 | |
| 028000–02FFFF | 32,768 | 000000101 | |
| 030000–0303FF | 1,024 | 00000011000000 | |
| 032000–032FFF | 4,096 | 000000110010 | |
| 034000–034FFF | 4,096 | 000000110100 | |
| 035000–0353FF | 1,024 | 00000011010100 | |
| 036000–036FFF | 4,096 | 000000110110 | |
| 038000–038FFF | 4,096 | 000000111000 | |
| 03E000–03EFFF | 4,096 | 000000111110 | |
| 040000–040FFF | 4,096 | 000001000000 | |
| 042000–042FFF | 4,096 | 000001000010 | |
| 044000–044FFF | 4,096 | 000001000100 | |
| 046000–046FFF | 4,096 | 000001000110 | |
| 048000–0483FF | 1,024 | 00000100100000 | |
| 04A000–04A3FF | 1,024 | 00000100101000 | |
| 04C000–04CFFF | 4,096 | 000001001100 | |
| 050000–050FFF | 4,096 | 000001010000 | |
| 054000–054FFF | 4,096 | 000001010100 | |
| 058000–058FFF | 4,096 | 000001011000 | |
| 05A000–05A3FF | 1,024 | 00000101101000 | |
| 05C000–05CFFF | 4,096 | 000001011100 | |
| 05E000–05E3FF | 1,024 | 00000101111000 | |
| 060000–0603FF | 1,024 | 00000110000000 | |
| 062000–062FFF | 4,096 | 000001100010 | |
| 064000–064FFF | 4,096 | 000001100100 | |
| 068000–068FFF | 4,096 | 000001101000 | |
| 06A000–06A3FF | 1,024 | 00000110101000 | |
| 06C000–06CFFF | 4,096 | 000001101100 | |
| 06E000–06EFFF | 4,096 | 000001101110 | |
| 070000–070FFF | 4,096 | 000001110000 | |
| 074000–0743FF | 1,024 | 00000111010000 | |
| 076000–0763FF | 1,024 | 00000111011000 | |
| 078000–078FFF | 4,096 | 000001111000 | |
| 07A000–07A3FF | 1,024 | 00000111101000 | |
| 07C000–07CFFF | 4,096 | 000001111100 | |
| 080000–080FFF | 4,096 | 000010000000 | |
| 084000–084FFF | 4,096 | 000010000100 | |
| 088000–088FFF | 4,096 | 000010001000 | |
| 08A000–08AFFF | 4,096 | 000010001010 | |
| 08C000–08CFFF | 4,096 | 000010001100 | |
| 090000–090FFF | 4,096 | 000010010000 | |
| 094000–0943FF | 1,024 | 00001001010000 | |
| 096000–0963FF | 1,024 | 00001001011000 | |
| 098000–0983FF | 1,024 | 00001001100000 | |
| 09A000–09AFFF | 4,096 | 000010011010 | |
| 09C000–09CFFF | 4,096 | 000010011100 | |
| 09E000–09E3FF | 1,024 | 00001001111000 | |
| 0A0000–0A7FFF | 32,768 | 000010100 | |
| 0A8000–0A8FFF | 4,096 | 000010101000 | |
| 0AA000–0AA3FF | 1,024 | 00001010101000 | |
| 0AB000–0AB3FF | 1,024 | 00001010101100 | |
| 0AC000–0ACFFF | 4,096 | 000010101100 | |
| 0AE000–0AEFFF | 4,096 | 000010101110 | |
| 0B0000–0B0FFF | 4,096 | 000010110000 | |
| 0B2000–0B2FFF | 4,096 | 000010110010 |
Checked October 13, 2026
Type an aircraft's 24-bit Mode S or ADS-B address in hex, octal or binary to see the country block it belongs to.
How to use
- Copy the aircraft's address from a flight tracker or ADS-B receiver, such as 461F2B, and type it in.
- If your transponder panel or log shows it in octal or binary, choose that notation first.
- Read the country whose block the address is in, with the block's range and the address in every notation.
How it works
Every aircraft with a Mode S transponder or ADS-B sends one 24-bit address, its "hex code". ICAO hands out these addresses in blocks to the States that register aircraft, and each State gives one address from its block to each aircraft on its register. So the address shows which country's block it comes from.
A block is fixed by the address's first 4, 6, 9, 12 or 14 bits; the remaining bits are free, giving blocks of 1,048,576 down to 1,024 addresses. Example: 461F2B in binary is 0100 0110 0001 1111 0010 1011. It starts with 010001100, Finland's block, so every address from 460000 to 467FFF (32,768 addresses) is Finnish. Octal and binary are the same number written another way: 461F2B is 21417453 in octal.
The block names the State of registry, never the aircraft, its owner or who flies it: only the State's own register links an address to one aircraft. When an aircraft moves to another country's register it gets a new address. The table here is ICAO Annex 10, Volume III, Table 9-1; ICAO may have allocated more blocks since, and unallocated blocks are kept as spares for each ICAO region.
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Frequently asked questions
Can I find out who owns the aircraft from its address?
Not here. The address only tells which State's block it is in. Some registers, such as the FAA's, publish the address of each aircraft, but this tool doesn't look anyone up and sends nothing anywhere.
Why does a flight tracker show a different country than the airline's home?
The address follows the aircraft's register, not the airline. A leased aircraft can be registered, and addressed, in another country than the one its operator comes from.
What is the difference between the address and a squawk code?
A squawk is a four-digit Mode A code that air traffic control assigns for a flight and can change. The 24-bit address is fixed to the aircraft and changes only when it moves to another register.
Why do some addresses start with A?
The United States has the largest block, every address from A00000 to AFFFFF. Russia has 100000 to 1FFFFF, and China, Canada, Australia and several large European States have blocks of 262,144 addresses.
How do I read an aircraft's registration mark, like OH-ABC?
The letters before the hyphen are the nationality mark: OH is Finland, D Germany and N the United States. The aircraft prefixes table in the country codes tool lists them all.
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