IPv4 subnet calculator
Find the network, broadcast, mask, and usable hosts of an IPv4 CIDR.
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Tool guide
IPv4 subnet calculator: how it works
Practical information to understand the result and use this tool correctly.
About IPv4 subnet calculator
The prefix length builds the mask. The network is the address AND the mask. The broadcast is the network OR the wildcard.
Prefixes /0 to /30 reserve the network and broadcast, so usable hosts are 2^(32-prefix) minus 2.
/31 follows RFC 3021 and treats both addresses as hosts. /32 is a single host. Empty input does not invent a network.
How to use it
- 1Type an IPv4 address and prefix, such as 192.168.1.10/24.
- 2Read the mask, network, broadcast, and usable range.
- 3Copy the summary. Nothing is uploaded.
Frequently asked questions
- What does 192.168.1.10/24 return?
- Network 192.168.1.0, mask 255.255.255.0, broadcast 192.168.1.255, usable 192.168.1.1–192.168.1.254 (254 hosts).
- Why does /31 show 2 hosts?
- RFC 3021 uses both addresses on a point-to-point link. There is no reserved network or broadcast.
- Does this support IPv6?
- No. This calculator is IPv4 only and does not look up who owns the range.