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

Multiply each octet by its place value and add: a x 16777216 + b x 65536 + c x 256 + d. For example, 192.168.1.1 is 3232235777.

What is an IPv4-mapped IPv6 address?

It is an IPv6 address of the form ::ffff:a.b.c.d that represents an IPv4 address, used by dual-stack sockets so IPv6 software can handle IPv4 peers.

Are IP address classes still used?

Classful addressing was replaced by CIDR in 1993, so classes A to E no longer determine network size. They are still shown because the terms appear in older documentation.

IP to Decimal, Hex & Binary Converter (IPv4)

Convert IPv4 addresses between decimal, binary, hexadecimal, octal, and IPv6 representations.

About IPv4 address converter

Converts an IPv4 address between dotted decimal, a 32-bit integer, hexadecimal, binary, octal and their dotted forms. It also shows the IPv4-mapped IPv6 address in short, hex and full notation, the 6to4 prefix and the reverse DNS (in-addr.arpa) name, along with the address class and special-purpose scope such as private, loopback or CGNAT. Input can be dotted decimal, an integer, or 0x, 0b or 0o prefixed values.

Common uses

Convert an IP address stored as an integer in a database back to dotted form
Get the binary form of an address to reason about subnet masks
Build the in-addr.arpa name for a PTR record
Write the IPv4-mapped IPv6 form (::ffff:a.b.c.d) of an address

FAQ

How do I convert an IP address to a decimal number?: Multiply each octet by its place value and add: a x 16777216 + b x 65536 + c x 256 + d. For example, 192.168.1.1 is 3232235777.
What is an IPv4-mapped IPv6 address?: It is an IPv6 address of the form ::ffff:a.b.c.d that represents an IPv4 address, used by dual-stack sockets so IPv6 software can handle IPv4 peers.
Are IP address classes still used?: Classful addressing was replaced by CIDR in 1993, so classes A to E no longer determine network size. They are still shown because the terms appear in older documentation.