IP Subnet Calculator

How a subnet is calculated

The prefix says how many leading bits of the address identify the network. The network address is the IP address with all host bits set to 0, and the broadcast address has all host bits set to 1. The wildcard mask is the netmask with its bits flipped.

The usable hosts lie between the network and broadcast addresses, so a subnet holds 2 to the power of the host bits, minus two. Two exceptions apply: a /31 point-to-point link (RFC 3021) has two usable addresses, both ends of the range, and a /32 is a single host, where the network, broadcast and host address are the same.

Formulas used

Network = IP AND Netmask
Broadcast = Network OR Wildcard
Total addresses = 2^(32 − prefix)
Usable hosts = 2^(32 − prefix) − 2  (/31: 2, /32: 1)

Worked example

The address 192.168.1.10 with a /24 prefix:

Netmask: 255.255.255.0; wildcard: 0.0.0.255
Network: 192.168.1.10 AND 255.255.255.0 = 192.168.1.0
Addresses: 2^8 = 256, so 254 usable hosts from .1 to .254

192.168.1.10/24 is in network 192.168.1.0/24 with 254 usable hosts.

Assumptions and limits

Only IPv4 is supported; IPv6 is not included.
Octets with leading zeros are rejected because some systems read them as octal.
Netmasks must be contiguous (all 1 bits first).
For /31 and /32 the first and last host follow RFC 3021 and single-host conventions; some older equipment may not accept /31 links.

Your address

Result