Question 1

How do I convert an IP address to a decimal number?

Accepted Answer

An IPv4 address is a 32-bit number written as four octets. To convert a.b.c.d to decimal, compute a*16777216 + b*65536 + c*256 + d. For example, 8.8.8.8 = 8*16777216 + 8*65536 + 8*256 + 8 = 134744072. The reverse splits the integer back into four bytes.

Question 2

Why would an IP address be written as a single number?

Accepted Answer

Databases and geolocation tables often store IPv4 addresses as 32-bit integers because integer comparison and range lookups are fast. Browsers also accept the integer form in URLs (http://134744072 resolves to 8.8.8.8), which is why attackers sometimes use decimal or hex IPs to obfuscate phishing links — a good reason to be able to decode them.

Question 3

Does this converter work for IPv6 addresses?

Accepted Answer

No — this tool is IPv4-only. IPv6 addresses are 128-bit values with their own hexadecimal colon notation (e.g. 2001:4860:4860::8888), so a 32-bit decimal/binary conversion does not apply. The dotted, integer, hex, and binary forms here all describe the same 32-bit IPv4 value.

IP位址進位轉換器

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