Read IP ranges, masks and address capacity
- Choose IPv4 or IPv6, then enter an address/CIDR or a separate prefix.
- Or choose Suggest IPv4 mask by host count, enter required LAN hosts or total IP addresses, and optionally check a parent CIDR.
- For IPv4, a contiguous dotted subnet mask can replace the prefix. The linked field updates the derived result.
- Read network range, exact total address count and the applicable host convention.
- Optionally split into equal longer prefixes. Browse and copy only a bounded page of child subnets.
Formats, output and limits
IPv4 decimal octets and prefixes 0–32, or IPv6 full/compressed and embedded IPv4 forms with prefixes 0–128. Address/CIDR limit 64 characters; prefix/mask limit 15. Sizing accepts a positive whole count up to 4,294,967,294 LAN hosts or 4,294,967,296 total addresses, at most 10 digits. No hostname, URL, leading-zero IPv4, scope suffix or network lookup. Subdivisions show at most 32 rows per page.
A worked example
192.0.2.130/26 belongs to 192.0.2.128/26. Its 64 addresses run through 192.0.2.191; the conventional host range is .129–.190 (62 hosts). Sizing for 50 LAN hosts suggests /26 (255.255.255.192), with 12 spare host slots; inside 192.0.2.0/24 its first matching block is 192.0.2.0/26. A /31 instead has two point-to-point endpoints. 2001:db8::/64 contains exactly 18,446,744,073,709,551,616 addresses.
Common questions
Can it suggest a mask for a required host count?
Yes. Select the host-count task. Usable LAN hosts reserves network and broadcast; total IP addresses counts the whole block. An optional parent CIDR checks fit and shows its first aligned matching block. Existing assignments are not checked. Include gateways and other devices in your requirement; IPv6 analysis remains separate.
Is every address counted usable?
No. IPv4 conventional capacity excludes network/broadcast endpoints, while /31 and /32 have specific conventions. Special-use ranges and deployment policies still matter. IPv6 total addresses are not a universal assignable-host count.
Does IPv6 have a broadcast address?
No. The tool reports address-space boundaries and exact counts without subtracting IPv4-style broadcast endpoints.
Does this find my gateway or devices?
No. It only calculates from entered text. There are no DNS queries, detected public IPs, scans or inferred gateway settings.