AS Number Calculator

Convert Autonomous System (AS) numbers between decimal, hexadecimal, and ASPLAIN formats. Essential for BGP configuration and troubleshooting.

Enter AS Number:

Input Format:

Decimal ASDOT Hexadecimal

Decimal (ASPLAIN): -

ASDOT Format: -

Hexadecimal: -

About AS Numbers

What an AS number is
An Autonomous System (AS) number identifies a routing domain in BGP — it represents administrative control over routing policies.
Common formats
ASPLAIN (decimal), ASDOT (X.Y), and hexadecimal — ASPLAIN is the preferred modern format.
Private ranges
16-bit private: 64512–65534. 32-bit private: 4200000000–4294967294. Strip private ASNs before advertising publicly.
Operational use
AS numbers appear in the AS_PATH attribute and are used for loop prevention and traffic policy (prepend/filter/match).