IP Subnet Calculator
Calculate subnet details from CIDR or dotted-mask notation.
Accepts CIDR (x.x.x.x/n) or dotted mask (x.x.x.x y.y.y.y)
/24 — Class C
Net: 11000000.10101000.00000001.00000000
Mask: 11111111.11111111.11111111.00000000
How subnet calculation works
CIDR (Classless Inter-Domain Routing) notation expresses an IP range as an IP address plus a prefix length — e.g. 192.168.1.0/24. The prefix (/24) is the subnet mask in bits: /24 = 255.255.255.0. You can also enter the mask in dotted decimal: 192.168.1.0 255.255.255.0. The calculator derives network address (IP & mask), broadcast (network | ~mask), first/last usable hosts, total host count, hex representations, IP type (private/public/loopback), and the reverse DNS delegation zone. For networking tools, also try Random IP Generator or Common Ports Reference.
Private & free — this tool runs entirely in your browser.