Calculate Subnet Masks
Convert CIDR notation to subnet masks and calculate usable host ranges.
Subnet Mask
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Total Hosts
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Usable Hosts
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The Methodology
Binary bitmask calculation
This tool uses the verified professional formula shown above. We cite our sources so you can trust every result.
Networking made simple
Calculating subnets manually is prone to error. Use this tool to quickly verify your network configurations and host limits.