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CIDR – Subnet – IP Calculator

Calculate IPv4 and IPv6 subnets instantly—free, accurate, private, and no sign-up required.

Made with ❤️ the StrongDM way: fast, simple, secure.

How to Use This Tool

1. Enter an IP Address: Input either an IPv4 (e.g., 192.168.1.0) or IPv6 (e.g., 2001:db8::) address.

2. Specify the CIDR: Choose the CIDR value (/1 to /32 for IPv4, /1 to /128 for IPv6).

3. Click “Calculate”: Instantly generate detailed subnet information including network address, usable IP range, broadcast address, and more.

4. View Results: Your subnet details will appear in the results box below.

5. Copy Results: Click “Copy Result” to use the subnet data wherever you need it.

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IP - Subnet - CIDR Calculator: FAQ

A subnet calculator is a tool that helps you determine network details—such as subnet mask, network and broadcast addresses, and host ranges—based on an IP address and CIDR notation.

Yes. You can enter either IPv4 or IPv6 addresses, and the tool will automatically calculate the correct subnet details for each protocol.
CIDR (Classless Inter-Domain Routing) notation defines the number of bits used for the network portion of the address. For example, /24 in IPv4 means the first 24 bits are reserved for the network.
Subnetting allows you to divide large networks into smaller, more manageable segments. It helps with efficient IP address allocation, improved security, and reduced broadcast traffic.
For IPv4, it includes the subnet mask, network and broadcast addresses, usable host range, total hosts, IP class, and more. For IPv6, it provides the full expanded address, network, range, and total addresses.
No. All calculations happen locally in your browser. No IP addresses or results are transmitted or stored.
Yes, it’s accurate and supports both IPv4 and IPv6. However, always validate with your network architecture team before applying to live environments.
The tool will notify you with an error message and ask you to enter a valid IPv4 or IPv6 address and CIDR value.

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