IP-Pal Gokul.IT.com · Tools

IPv4 Subnet Calculator

Enter an address with a CIDR prefix to see the full subnet breakdown. Adjust prefix live with slider.

Examples: 10.0.0.0/8, 192.168.1.10/30

/24

Help & reference

Privacy & Security

  • All calculations run locally in your browser.
  • Nothing ever leaves your device — No uploads, No servers, No logs, No file names collected.
  • No account required. No login. No email.

What is CIDR?

CIDR notation (e.g. /24) states how many leading bits of an address identify the network. The remaining bits identify hosts within that network.

IPv4 vs IPv6

IPv4 addresses are 32 bits (four octets, 0–255 each). IPv6 addresses are 128 bits, written as eight groups of hexadecimal digits, built to give every device a globally unique address.

Network & broadcast address

The network address is the first address in a subnet (all host bits zero). The IPv4 broadcast address is the last address (all host bits one) and reaches every host on that subnet. IPv6 has no broadcast address.

Usable hosts, /31, and /32

Usable hosts normally excludes the network and broadcast addresses. A /31 is a two-address point-to-point link (RFC 3021) where both addresses are usable. A /32 identifies a single host.

IPv6 /64 and compression

Most IPv6 subnets use a /64, leaving 64 bits for host addressing. Compression replaces one run of consecutive all-zero groups with :: to shorten the address; only the first, longest such run is compressed.

Subnet Planning & VLSM

Equal subnetting slices a network block into equal portions. Variable Length Subnet Masking (VLSM) dynamically assigns different prefix lengths based on exact host requirements to minimize wasted IP space.

Multi-Format IP Representations

An IP address is fundamentally a 32-bit (IPv4) or 128-bit (IPv6) binary number. It can be expressed in decimal, hexadecimal, binary, octal, or as reverse DNS pointer (PTR) records for in-addr.arpa and ip6.arpa.