CIDR Calculator
Calculate IP address range by CIDR notation.
CIDR calculator: CIDR to IP range
Enter a block in CIDR notation, such as 203.0.113.0/22, and get its range: network address, first and last host, broadcast, total addresses and how many you can assign to devices. Your prefix is highlighted in the reference table. IPv4 only. For a detailed look at a network around a specific address, use the subnet calculator.
CIDR to IP range conversion
Total addresses and usable hosts in the block
Subnet mask and wildcard mask
How to Use
- Enter a block in CIDR format, e.g. 192.168.1.0/24
- Read the first and last address of the range
- Compare total addresses with usable hosts
FAQ
Enter a block such as 10.20.0.0/22. The calculator zeroes the host bits to get the network address 10.20.0.0 and sets them to one to get the last address 10.20.3.255. That is 1,024 addresses.
Total is 2^(32 − prefix). The network and broadcast addresses are not assigned to devices, so there are 2 fewer usable hosts. /31 and /32 are exceptions with 2 and 1 addresses.
The number after the slash is how many leading bits are fixed. /0 is the entire IPv4 internet, /8 is 16.7 million addresses and /32 is one address. This is how ranges are written in firewall rules, cloud security groups and IP allowlists.
No, the calculator handles IPv4 only and expects the a.b.c.d/prefix format.