CIDR Toolbelt
Merge, overlap-check, and diff IPv4 CIDR lists for security groups.
OpenCalculate IPv4 network, broadcast, and host ranges from CIDR. - runs entirely in your browser. Free, fast and private.
Type an IPv4 address with prefix like 192.168.1.0/24.
Subnet mask, network, broadcast, and host range derive locally.
Usable hosts and wildcard mask display in a summary table.
Paste ranges into firewall rules or IP plans.
Subnet Calculator is a free network & ops utility on OneDevToolkit. Calculate IPv4 network, broadcast, and host ranges from CIDR. It runs in your browser for this session - use the workspace on this page to try it.
Need a related step? Open the Network & Ops hub at /network-tools/ or the <a href="/blog/">blog</a> for longer workflows.
Processes data instantly with no server round-trips.
Your data never leaves your browser. Nothing is uploaded.
Works in any modern browser. Nothing to download or install.
No limits, no sign-up, no credit card required.
Works on desktop, tablet and mobile devices.
Beautiful in both themes. Your preference is saved.
Keyboard shortcut
Open Subnet Calculator when you need a quick result without uploading data to a third-party site.
No install required - bookmark the tool and return anytime.
Client-side processing keeps inputs on your device for core OneDevToolkit tools.
Answers for this tool. For site-wide help, open the FAQ hub.
Subnet Calculator calculate ipv4 network, broadcast, and host ranges from cidr. Output stays in your browser for quick iteration.
Prefer redacted samples. Even with local processing, treat prod credentials carefully and rotate anything accidentally shared.
No. Generators and linters produce text for you to copy into Git, CI, or consoles - they do not deploy for you.
Always run official CLIs (kubectl, terraform plan, actionlint, etc.) on the final files after using Subnet Calculator as a starting point.
Syntax may vary across Kubernetes/Terraform/GitHub Actions versions. Adjust generated snippets to your runtime version.
After the page loads, most authors work offline. Keep a local copy of critical manifests.
Use Sample to learn the format, edit, then Download/Copy into your editor.
Request it via Contact with the platform and version you use.