How to use it
- Choose IPv4 or IPv6 and enter an address.
- Provide a CIDR prefix or IPv4 mask.
- Review network details or select a longer prefix to split the network.
Runs locally in your browser
IP subnet calculator
Calculate IPv4 network, broadcast, wildcard and hosts, or IPv6 canonical and expanded addresses. CIDR, masks and subnet splitting online.
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Accurate IPv4 and IPv6 calculations
See network boundaries and usable addresses with correct point-to-point /31 and single-host /32 handling. Binary output makes network and host bits easy to understand.
IPv6 calculations preserve full 128-bit precision. Results include compressed and expanded forms and the address scope or category.
- IPv4 and IPv6
- CIDR, netmask and wildcard
- Correct /31 and /32 handling
- Subnet splitting
Frequently asked questions
Why does /31 have two usable addresses?+
RFC 3021 defines /31 as a two-address point-to-point link. Separate network and broadcast addresses are not reserved in this case.
What is a wildcard mask?+
A wildcard is the inverse mask with host bits set. For example, netmask 255.255.255.0 corresponds to wildcard 0.0.0.255.
Does IPv6 use broadcast?+
No. IPv6 uses multicast and related mechanisms instead of broadcast, so IPv4-only fields are not presented as IPv6 equivalents.