About CIDR to IP Range Converter

Converts CIDR notation (like 192.168.1.0/24) into its full IP range using bitwise arithmetic. Calculates the network address, broadcast address, subnet mask, wildcard mask, total IPs, usable host IPs (total minus network and broadcast), network class (A through E by first-octet range), and whether the address is private (RFC 1918) or public. IPv4 only.

• Bitwise CIDR math: IP octets are combined via left-shift into a 32-bit integer, masked against 0xFFFFFFFF << (32 – prefix), then extracted back to dotted-quad notation
• Outputs: first usable IP, last usable IP, network address, broadcast address, subnet mask, wildcard mask
• Total IPs = 2^(32 – prefix); usable IPs = total – 2 (excludes network and broadcast addresses)
• Network class detection: Class A (1–126), B (128–191), C (192–223), D (224–239 multicast), E (240–255 reserved)
• RFC 1918 private range detection: 10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16
• Reference tables for common CIDR blocks, RFC 1918 ranges, and subnet masks

Frequently Asked Questions

Does it support IPv6?

No, IPv4 only. IPv6 CIDR math requires 128-bit integers, which JavaScript’s standard Number type can’t handle. You’d need BigInt-based arithmetic or a dedicated library.

Why are there 2 fewer usable IPs than total?

The first address in any subnet is the network address (identifies the subnet itself) and the last is the broadcast address (sends to all hosts on the subnet). Neither can be assigned to a host. A /24 has 256 total addresses but only 254 usable.