Packetrove

IP ADDRESS TOOLS

CIDR Subtraction

Subtract excluded IPv4 or IPv6 networks from your included address space. Get the smallest exact CIDR list, with no added addresses.

Calculated in your browser · No API request

Your address lists

Separate entries with commas, spaces, tabs, or line breaks. Include at least one address or range.

Separate entries with commas, spaces, tabs, or line breaks. Leave empty to simplify the include list without removing addresses.

Use one address family and at most 1,000 entries across both lists, with at most 64 characters per entry. Results may contain up to 10,000 CIDRs; larger results return an error with no partial list.

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Remaining address space

Your result will appear here

Enter an include list and optional exclusions to calculate the exact remainder.

What the result means

The calculation subtracts the union of exclusions from the union of included ranges. Overlaps count once, host bits are normalized, and no addresses are added. All addresses in a range count, including network and broadcast addresses.

Use the result for WireGuard exceptions or to inspect gaps after known allocations. Gaps are relative to your inputs; they do not prove addresses are unused on the live network. Review the list before applying it.