CIDR / Subnet Calculator

Calculate IPv4 network address, netmask, broadcast, usable host range, and optional subnet splits from a CIDR block.

CIDR / Subnet Calculator

Network address, broadcast, usable hosts, wildcard mask, and subnet splits for IPv4 CIDR blocks.

IPv4 only. /31 and /32 follow RFC 3021-style point-to-point / host semantics for usable counts.

Typical Uses

  • Sizing AWS VPC / subnet CIDRs
  • Checking whether a host IP falls in a range (compare network & broadcast)
  • Splitting a /16 into /20 or /24 blocks for environments

IPv6 is not covered here — use dedicated IPv6 tooling for those ranges.