Online IP Subnet Calculator
Enter a CIDR block or subnet mask to get the network, broadcast and usable host range instantly. 100% private, all processing in your browser
Frequently Asked Questions
Two formats: CIDR slash notation (e.g. 192.168.1.0/24) and IP plus dotted-decimal netmask (e.g. 192.168.1.0 255.255.255.0). The mask must be a contiguous run of ones.
Hosts = 2^(32-prefix) - 2, subtracting the network and broadcast addresses. A /24 has 254 usable hosts; /31 and /32 have none.
No. All subnet math happens locally in your browser. IP data never leaves your device, fully protecting your privacy.
RFC1918 ranges 10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16, plus loopback 127.0.0.0/8 and link-local 169.254.0.0/16. The tool flags these automatically.
The current version covers IPv4 subnetting. IPv6 addressing works differently and may be added in a future release.
Completely free. This is a pure frontend online tool - no registration required, no payment needed, just open and use.
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