Subnet Calculator
Derive network, broadcast, host range and masks from CIDR notation — IPv4 and IPv6, all in your browser.
IPv4 CIDR
About this tool
Calculate IPv4 and IPv6 subnets from CIDR notation — network address, broadcast, usable host range, subnet mask, wildcard mask, and a visual bit map Subnet Calculator runs in the browser on DevTools. There is no signup, and your input stays on this device unless the tool explicitly performs a live network lookup.
What this tool does not do
- Subnet Calculator is a free in-browser utility, not a hosted API. It does not keep server-side history and is not a substitute for production verification in your own stack.
How do I use this tool?
How do I use Subnet Calculator?
Open Subnet Calculator, enter or paste your input, and copy the result. The page works without an account.
Related guides
IPv6 Addressing Explained: Expanding and Compressing Addresses
How IPv6 addresses are structured, the rules behind the :: shorthand and leading-zero omission, and how to canonicalize an address per RFC 5952.
Subnetting Without the Headache: A Practical CIDR Guide
How CIDR notation, subnet masks, network and broadcast addresses actually work — with the /31 and /32 edge cases most people get wrong.
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