How to use the CIDR calculator

What does /24 mean?

A /24 IPv4 network contains 256 addresses. For example, 192.168.1.0/24 runs from 192.168.1.0 to 192.168.1.255 and has subnet mask 255.255.255.0.

Total addresses and usable hosts

For conventional subnets through /30, the network and broadcast addresses are excluded from the usable host count. A /31 point-to-point link has two addresses; a /32 identifies one address.

Convert a range to CIDR

Enter the first and last IPv4 addresses. Both endpoints are included. The result may contain several CIDR blocks so that no addresses outside the range are added. Calculations run in your browser.