CIDR / Subnet Calculator
Break down any IPv4 CIDR block into network and broadcast addresses, usable host range, host count, and netmask. Runs entirely in your browser.
NetworkingCIDR Calculator
Analyze a single IPv4 CIDR block: network, broadcast, mask, and host range.
Runs locally. Nothing is sent to any server.
What this page needs
This tool computes entirely on your device, so nothing you type is sent anywhere. That local computation needs JavaScript; CSS is used for layout and theming.
This tool is built to also work over an HTTP API. Processing is currently off, so the API is documented but not served; when it is switched on, you will be able to call it without a browser.
All results are computed locally from the address and prefix you enter, using standard IPv4 addressing arithmetic. Nothing is looked up remotely and nothing is sent anywhere.
- RFC 4632 (CIDR)Classless Inter-Domain Routing address aggregation
- RFC 1918Private address ranges
- RFC 791 (IPv4)The Internet Protocol