VLSM / Subnet Divider
Enter a base network and list your subnet requirements — label each one and set the host count. The calculator sorts by size (largest first), then allocates the smallest prefix that fits, placing subnets contiguously and flagging any that overflow. Or switch to Equal Split mode to divide the base into N identical subnets.
Requirements are sorted largest-first before allocation. Minimum 1 host per subnet.
| Label | Network | CIDR | Mask | First host | Last host | Usable hosts | Broadcast |
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Click the copy icon on any row to copy that subnet's details to the clipboard.
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