IP Subnet Calculator
Work out the network, broadcast, mask and host range for any IPv4 subnet.
What a subnet is
A subnet is a block of IP addresses that share the same network part. The prefix length (CIDR) says how many of the 32 bits belong to the network. The rest identify hosts inside it.
Example
192.168.1.10/24 is in the network 192.168.1.0 with the mask 255.255.255.0. The broadcast address is 192.168.1.255, and the usable hosts run from 192.168.1.1 to 192.168.1.254, which is 254 addresses.
Handy rules
- Usable hosts = 2(32 − prefix) − 2. The first address is the network and the last is the broadcast.
- A /31 has 2 usable addresses for point-to-point links, and a /32 is a single host.
- The wildcard mask is the inverse of the subnet mask and is used in some router access lists.
Frequently asked questions
What does /24 mean?
The first 24 bits identify the network, leaving 8 bits for hosts. That equals the mask 255.255.255.0.
Does this support IPv6?
Not yet. This calculator covers IPv4 only.
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