IP Subnet Calculator

Free IPv4 subnet calculator: network and broadcast address, usable host range, mask, wildcard and binary for any IP and CIDR prefix, plus subnet splitting.

β€”Network address
β€”Broadcast address
β€”Usable host range
β€”Usable hosts
β€”Total addresses
β€”Subnet mask
β€”Wildcard mask
β€”Class
β€”Type

In binary

 
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What it does
A CIDR prefix such as /24 says how many leading bits of the address belong to the network. The rest identify hosts: the first address is the network itself and the last is the broadcast, so a /24 has 256 addresses and 254 usable hosts. A /31 is the exception used on point-to-point links, where both addresses are usable (RFC 3021).
How to use it
  1. Type an IP address with a CIDR prefix (10.0.5.20/22) or a subnet mask (10.0.5.20 255.255.252.0).
  2. Read the network, broadcast, host range, masks and the binary view.
  3. To plan addressing, choose a longer prefix to split the network into equal subnets.
Frequently asked questions
How many hosts are in a /24, /26 or /30?
A /24 has 254 usable hosts, a /26 has 62 and a /30 has 2. The formula is 2 to the power of (32 − prefix), minus the network and broadcast addresses.
What is a wildcard mask?
It is the subnet mask with every bit inverted: 255.255.255.0 becomes 0.0.0.255. Cisco access lists and OSPF use it to say which bits of an address must match.