About cidrcalculator.net

Our mission

cidrcalculator.net was built to solve a small but persistent frustration: existing subnet calculators were either feature-poor, visually dated, or hidden behind enterprise pricing. We set out to build one tool that does everything an engineer needs — IPv4, IPv6, VLSM, cloud-aware sizing, Infrastructure-as-Code export, validation, and visualization — and keep it free to use.

What makes us different

• Comprehensive — over 60 features across calculation, design, validation, and export
• Cloud-aware — built-in rules for AWS, Azure, GCP, OCI and Kubernetes
• Client-side — all calculations happen in your browser; your CIDR ranges are not transmitted to our servers
• Standards-compliant — calculations follow RFC 1918, RFC 4632, RFC 6598, RFC 4291 and related standards
• Free to use — supported by non-intrusive advertising rather than subscriptions for core tools

Who we serve

Our users include:

• Network engineers managing enterprise WANs and LANs
• Cloud architects designing multi-cloud environments
• DevOps and platform engineers generating Terraform and CloudFormation
• Students preparing for CCNA, Network+, AWS Solutions Architect and similar certifications
• Educators teaching networking fundamentals
• Security teams reviewing ACLs and firewall rules

How we sustain the service

cidrcalculator.net is free for everyone. Core tools — calculator, VLSM designer, IPAM, IaC export, learning resources — are open and unrestricted. The site may carry display advertising in the future to support development costs; if it does, we'll disclose the networks in our privacy policy.

We make this trade-off intentionally: we believe basic subnet math should never be gated behind a paywall, and that an ad-supported model makes the tool more sustainable than a freemium model that would force key features behind subscriptions.

Accuracy & reliability

While we work hard to ensure correctness, cidrcalculator.net is provided as an aid, not as a substitute for professional network engineering judgment. We strongly recommend reviewing all results before applying them to production networks. See our disclaimer for full details.

Open standards

All calculations follow published RFCs. Where cloud-specific behavior differs (e.g., reserved IPs in AWS VPC), we cite the source provider's documentation. Where conventions exist (e.g., RFC 6598 CGNAT range), we apply them transparently and explain them in the Learn section.

Contact us

Have feedback, found a bug, or want to suggest a feature? We'd love to hear from you. Visit the contact page or email contactus@cidrcalculator.net.