CIDR Subnet Calculator

Calculate subnet masks, network ranges, usable IPs, and wildcard masks from CIDR notation. The CIDR Subnet Calculator is one of 900+ free developer tools on Toolblip - all open to use without a signup.

Open the CIDR Subnet Calculator on this page, paste or upload your input, and the result updates as you type. Use the copy button to grab the output, or adjust options to tune the result. Nothing you enter leaves your browser.

Yes. The CIDR Subnet Calculator is a free online tool on Toolblip - no signup, no account, no hidden usage limits. It runs in your browser and works on desktop and mobile.

Yes. The CIDR Subnet Calculator processes your data entirely client-side, so nothing you paste is uploaded or stored on any server. It's safe to use with internal snippets, private keys for debugging, or any other sensitive content you'd rather not send to a remote service.

Only where the task requires it (for example, looking up a DNS record). The interface and any parsing happen in your browser, and Toolblip doesn't log the queries you make.

Once the page has loaded, the CIDR Subnet Calculator continues to work without an internet connection. Bookmark this page and return to it anytime - all logic runs locally.