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IP Subnet Calculator

Calculate network address, broadcast, host range, subnet mask and more from a CIDR notation or separate IP + mask.

CIDR Notation

IP + Prefix Length

About IP Subnet Calculator

IP Subnet Calculator is a free, browser-based utility built for developers and engineers who need a fast, reliable way to calculate network address, broadcast, host range, subnet mask and more from a cidr notation or separate ip + mask. Whether you're debugging an API response, preparing data for deployment, or validating configuration files, this tool handles the job in seconds — with zero server calls. Everything runs locally in your browser, so your source code and data stay private.

How to Use

Enter or paste your input Type or paste your data into the input area. You can also use keyboard shortcuts (Ctrl+V) for quick pasting.

Configure options Adjust any settings or options above the input area to customize the output format and behavior.

Process your data Click the primary action button to process your input. The result appears instantly — no server round-trips.

Review the output Check the output area for your processed result. Any errors or warnings will be displayed clearly.

Copy or download Use the Copy button to copy the result to your clipboard, or download it as a file if that option is available.

🔒 Privacy note: All processing happens locally in your browser. Your data is never sent to any server.

Why Use IP Subnet Calculator?

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Instant Results, Zero Setup No need to install CLI tools, configure environments, or write scripts. IP Subnet Calculator gives you the result instantly in your browser — paste, click, done.

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Your Code Stays Private All processing runs locally using JavaScript. Your source code, API keys, tokens, and configuration data never leave your browser — not even temporarily.

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Part of Your Dev Workflow Bookmark this tool alongside your IDE and terminal. When you need a quick format, encode, or validation, it's one tab away — faster than installing yet another npm package.

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Use It Anywhere Works on any device with a modern browser — laptop, tablet, or phone. Perfect for quick fixes when you're away from your development machine.

Frequently Asked Questions

CIDR (Classless Inter-Domain Routing) notation combines an IP address with a prefix length (e.g. 192.168.1.0/24). The prefix length (0–32) tells you how many bits are the network portion — the rest are for host addresses.

The first address (network address) and last address (broadcast address) cannot be assigned to hosts. The network address identifies the subnet itself, and the broadcast address is used to send packets to all hosts on the subnet.

A wildcard mask is the inverse of the subnet mask. It's used in Cisco ACLs and OSPF configurations. Where the subnet mask has 1s (network bits), the wildcard has 0s, and vice versa.