Network Design StudioPublic beta

Engineering tools / IP address planning

Find the next free subnet

Plan IP address space without guessing overlaps. Choose a network goal or enter exact CIDR and dotted-mask ranges; receive a source-labelled, aligned suggestion with an undoable local plan.

1. Describe your network
Try clearly illustrative example inputs, then adjust them to your plan. No sign-in or remote connection.

Changing the example replaces this local working draft; expert edits are preserved when switching modes.

For example, 192.168.10.0/24 or 192.168.10.0/255.255.255.0. Use the network boundary.

Whole devices; one LAN block.

Adds address headroom, not bandwidth.

One CIDR or dotted mask per line, comma or semicolon (maximum 128). Duplicate, overlapping and out-of-parent allocations are rejected.

2. Review the available address space
Calculations update immediately when an input changes; no configuration is applied.
Calculated locally192.168.10.0/24 parent
Requested device addresses
50
Including headroom
60
Required block
/26
Parent total addresses
256
Reserved block addresses
64
Unallocated addresses
192
Allocated address space25.0%

This bar counts addresses in reserved blocks, including network and broadcast; holes may be fragmented.

Next aligned free block

192.168.10.64/26

Mask 255.255.255.192; 62 usable LAN addresses, from 192.168.10.65 to 192.168.10.126.

Inspect 1 reserved block(s)
  • 192.168.10.0/2664 addresses

Methodology and limitations

Uses deterministic IPv4 network arithmetic. Proposed blocks are planning suggestions, never real device inventory, DHCP allocations or cloud-specific reserved addresses.

For conventional LANs, two addresses are reserved for network and broadcast. /31 point-to-point and /32 host behavior can be inspected in the subnet calculator; they are not used as multi-device LAN suggestions.

References: RFC 4632 (CIDR) and RFC 3021 (/31). Cloud platform reservation rules differ and are not inferred.