Subnet / CIDR Calculator
Exact IPv4 subnet maths — network, broadcast, host range, masks, binary breakdown, subnet splitting and an in/out membership tester.
Each octet 0–255. Tip: paste a full 10.0.0.0/8 here.
Enter a full IPv4 address to test membership.
× networks · usable hosts each
🔒 100% in-browser, zero network calls — every value is exact 32-bit math. Handles /31 (RFC 3021, 2 usable) and /32 edge cases correctly. Where LLMs routinely fumble subnet boundaries and host counts, this is deterministic and instant.
Why you’ll love Subnet / CIDR Calculator
Instant & free
No signup, no paywall, no limits — Subnet / CIDR Calculator works the moment the page loads.
Completely private
Everything runs in your browser. Nothing you enter is ever uploaded or stored on a server.
Works on any device
Fully responsive and touch-friendly — use it on your phone, tablet or desktop.
Built by developers
Accurate, fast and keyboard-friendly — the details developers care about.
How to use it
Open it
No download and no login — the tool is ready right at the top of this page.
Use it
Enter your details or start interacting. Everything updates live as you go.
Get your result
Copy, download or share your result in a single tap. That’s it.
Frequently asked questions
Subnet / CIDR Calculator is 100% free — no signup, no watermarks and no usage limits. It’s one of 200+ free tools we build and give away.
Never. Everything is processed locally in your browser — safe for secrets, tokens and proprietary code.
Completely. Subnet / CIDR Calculator runs entirely in your browser (client-side). Nothing you type, upload or generate is sent to our servers, so your data never leaves your device.
No. It works instantly in any modern web browser — Chrome, Safari, Edge or Firefox — on desktop and mobile. You can even install this site as an app.
Yes. The tool is fully responsive and touch-friendly, so it works great on phones and tablets as well as computers.
Workaholic Developers — a software & AI studio. We built Subnet / CIDR Calculator (and 200+ other free tools) to show what we can do. Need something custom built? We’d love to help.
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