Built for engineers. Free forever.

Why this exists

Most subnet calculators feel like they were last updated in 2008. They give you the network address and broadcast, then call it a day — no cloud awareness, no VLSM, no exportable config, no learning path for newcomers. We built subnetmaskcalc.net because modern network engineers deserve modern tools.

What's different

• Cloud-aware math. AWS reserves 5 IPs per subnet. Azure reserves 5 with different rules. GCP takes 4. Most calculators ignore this and give you the wrong usable count.
• VLSM that actually works. Drop in your host counts, get back optimally-sized subnets with boundary alignment handled.
• IaC export. Terraform (AWS, Azure, GCP), CloudFormation, Bicep, Pulumi, Ansible, Cisco IOS, Kubernetes YAML — copy production-ready code instead of translating by hand.
• AI subnet designer. Describe your network in plain English, get a complete plan with reasoning. Runs entirely in your browser.
• A real Learn Center. 109 lessons, an interactive quiz, a /0–/32 reference, glossary, and a printable cheat sheet PDF — all free, all without an account.

Our commitments

1. No signup. Nothing is gated behind an account. Bookmark a calculator link and share it with your team.
2. Your inputs stay in your browser. Every CIDR, host count, and AI network description you enter is processed client-side. Calculations never reach our servers. Lesson progress and quiz streaks live only in your local storage.
3. Honest about ads & analytics. We run banner ads and Google Analytics so the toolkit can stay free. EU/UK/Swiss/California visitors get a consent banner; everyone can opt out via the "🍪 Cookies" button. Details are in our privacy policy.
4. Free forever. Including the IaC export, the AI assistant, and the Learn Center.

Who it's for

Network engineers planning VPCs and on-prem networks. Cloud architects laying out multi-account, multi-region topologies. DevOps and platform engineers planning Kubernetes pod and service CIDRs. Students preparing for CCNA, Network+, or AWS certifications. Honestly — anyone who needs to do subnet math without opening a spreadsheet.

How it's built

The entire site runs in your browser. No backend, no database for your calculations. The subnet math is plain JavaScript. The PDF cheat sheet is generated client-side with jsPDF. The AI subnet assistant is a rule-based NL parser, not a server-hosted LLM — your network description never leaves your device. (We do use Google Analytics to count page views and serve banner ads via Adsterra / AdSense to cover hosting; see the privacy policy for details.)

Get in touch

Found a bug? Have a tool idea? Want a blog post on a specific topic? Reach out via the contact page or email contactus@subnetmaskcalc.net.