IPv4 Subnet / CIDR Calculator
Subnet mask, network/broadcast, and usable host range from IP + CIDR prefix.
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Subnet mask255.255.255.0
Wildcard mask0.0.0.255
Network address192.168.1.0
Broadcast address192.168.1.255
First usable host192.168.1.1
Last usable host192.168.1.254
Usable host count254
Total addresses256
What is this tool?
CIDR notation (e.g. 192.168.1.0/24) combines an IP address with a prefix length describing how many leading bits identify the network. This calculator derives the subnet mask, wildcard mask, network and broadcast addresses, and the usable host range — correctly handling /31 (RFC 3021 point-to-point, both addresses usable) and /32 (a single host, no network/broadcast concept).
How to use it
- Enter an IPv4 address.
- Enter a CIDR prefix from 0 to 32.
- Read the subnet mask, network/broadcast addresses, and usable host range.
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