Start

Enter a parent IPv4 network and the host count for each requirement. Subnify validates the complete plan before it displays results or saves history.

CIDR

VLSM gives each requirement the smallest power-of-two block that fits its hosts plus reserved network and broadcast addresses. Larger host requirements allocate first; equal host counts keep input order. Parent prefixes may range from /0 through /30. This planner excludes /31 and /32 allocations.

Validation

Parent addresses must be canonical for their prefix. When an address is inside a network but not at its start, Subnify offers the canonical base. Parent capacity is its total address count; every child block must fit without overlap. Format, prefix, names, host counts, and capacity all validate before calculation.

Templates

Home lab, small office, and segmented office templates provide editable starting values. Replacing changed inputs always requires confirmation.

AI plans

Signed-in users can draft requirements from a prompt. Every draft appears as a preview and passes through the same deterministic calculation engine as manual input. Nothing changes until you choose Apply.

Results

Allocated addresses include each child block's network and broadcast reservations. Usable hosts exclude those two addresses. Efficiency is requested hosts divided by allocated addresses. Table values are exact; the map and hierarchy show allocated and free parent space.

Examples

192.168.1.0/24 with a 50-host LAN receives a /26: 64 allocated addresses, 62 usable hosts, and 192 addresses free. A /30 parent cannot fit 3 usable hosts because that requirement needs an 8-address /29 block.

History

Saved records retain title, source, parent network and prefix, requested subnets, calculated allocations, required and usable-host totals, and creation time. AI records also retain prompt and rationale. Confirmed deletion removes the cloud copy; copied results and exported PDFs remain.