Subnet Calculator (CIDR)
Calculate network address, broadcast address, subnet mask, and usable host range from an IP address and CIDR prefix — instantly, in your browser.
Calculate the network address, broadcast address, subnet mask, and usable host range from an IP address and CIDR prefix. Everything runs entirely in your browser.
How it works
Enter an IP address with a CIDR prefix, like 192.168.1.0/24, and this tool computes the network address, broadcast address, subnet mask, wildcard mask, and the usable host range for that block. /31 point-to-point links (RFC 3021) and /32 single-host blocks are handled correctly — both addresses in a /31 are usable, and a /32 has exactly one.
FAQs
What counts as a “usable” host?
For a normal subnet (prefix ≤ 30), the network address and broadcast address are reserved, so usable hosts is the total address count minus 2. /31 and /32 are special cases where every address in the block is usable.
Is my data sent anywhere?
No. The calculation happens entirely in your browser.