Subnet Calculator (CIDR)

Enter an IPv4 address with a CIDR prefix and see the network and broadcast addresses, the mask, the usable host range and the host count. It runs in your browser.

How to use it

1. Type an address and prefix, such as 192.168.1.0/24.
2. Read the network address, broadcast address, subnet mask, wildcard mask, usable range, usable hosts and total addresses.

Examples

• 192.168.1.0/24: mask 255.255.255.0, usable 192.168.1.1 to 192.168.1.254, 254 hosts.
• 10.0.0.0/22: mask 255.255.252.0, usable 10.0.0.1 to 10.0.3.254, 1,022 hosts.
• 192.168.1.77/30: belongs to the network starting at 192.168.1.76, with 192.168.1.79 as broadcast, so only .77 and .78 are usable.

Good to know

The number after the slash is how many bits identify the network. A /24 leaves 8 host bits, which is 256 addresses; two of them (the network and broadcast addresses) cannot be assigned, so 254 are usable. A bigger prefix number means a smaller network. The address you type can be any host inside the network. Special small prefixes such as /31 and /32 follow separate rules and IPv6 is not supported.

See the subnet guide and CIDR notation.

FAQs