CIDR Calculator

v1.0 · Everything below stays in your browser

Compute IP range, netmask, first/last usable address, and host count from a CIDR block.

Runs entirely in your browser · Your input is never transmitted

Network

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Netmask

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Broadcast

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Total hosts

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First usable

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Last usable

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Usable hosts

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Prefix

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How to use

IPv6 support?

IPv4 only in this tool. IPv6 uses a similar concept but the math is 128-bit — needs a different calculator.