CIDR / Subnet Calculator

Enter your IPv4 address and prefix length (CIDR); instantly see the network/broadcast address, mask, and usable host count.

Runs 100% in your browser — the IP you enter is never sent to a server.

Try This Next

Finished here? These might be your next step.

Hex ↔ TextConvert text to hexadecimal and back (UTF-8).Byte ConverterConvert between bytes, KB, MB, GB, TB (binary and decimal).HTTP Status CodesLook up all HTTP status codes (200, 404, 500…) with their meanings.

Frequently Asked Questions

Per RFC 3021, a /31 is a special case with only 2 addresses (for point-to-point links) — both addresses count as usable hosts, with no separate network/broadcast address reserved. A /32 designates a single host (a host route), so the concept of usable hosts doesn't apply.

The network address is the first address of a subnet and identifies the subnet itself (it can't be assigned to a device). The broadcast address is the last address of the subnet; it's used to send data to all devices on that subnet at once. Neither can be assigned as a regular host — that's why, in a /24 network for example, only 254 of the 256 addresses are usable.

Last updated: