IP to Binary Converter

Subnetting only makes sense once you see addresses as bits. This tool writes an IPv4 address as four 8-bit octets (and IPv6 as eight 16-bit groups), shows which place values make up each octet, and turns binary back into a normal address. Add a prefix such as /26 to see the network and host bits, the subnet mask in binary and the network address.

How to use this tool

1. Enter an address such as 192.168.1.10, optionally with a prefix length like /24.
2. Or paste binary — 32 bits, or four 8-bit groups separated by dots — to get the address back.
3. Read the octet table to see which place values (128, 64, 32 … 1) are switched on.
4. Paste several lines to convert a whole list.

Formula

octet = b₇×128 + b₆×64 + b₅×32 + b₄×16 + b₃×8 + b₂×4 + b₁×2 + b₀×1

Each IPv4 octet is a number from 0 to 255, written as exactly eight bits. With a /n prefix the first n bits are the network part: the subnet mask is n ones followed by zeros, and the network address is the address AND the mask, bit by bit. Leading-zero IPv4 octets are read as decimal. Paired IPv6 brackets are accepted; zone identifiers must be removed explicitly.

Example

For 192.168.1.130/25: 192 = 128 + 64 → 11000000, 168 = 128 + 32 + 8 → 10101000, 1 → 00000001 and 130 = 128 + 2 → 10000010. A /25 mask is 25 ones, 11111111.11111111.11111111.10000000 (255.255.255.128). In the last octet, 10000010 AND 10000000 = 10000000 = 128, so the network address is 192.168.1.128, leaving 7 host bits.