CIDR to IP Range Calculator
Enter a CIDR block and get the address range, masks and host count.
Result
Enter any IPv4 block. If the host bits are set, the tool shows the real network address, so 10.1.2.3/16 becomes 10.1.0.0/16. For /31 both addresses are usable (RFC 3021) and a /32 is a single host.
Common private ranges
192.168.1.0/24 | 192.168.0.0/24 | 192.168.0.0/16 | 10.0.0.0/8 | 172.16.0.0/12
Use the result in a firewall
Paste the block into the iptables generator as the source IP or subnet.
FAQ
How do I convert CIDR to an IP range?
Apply the prefix length to the address: the network address is the first IP and the broadcast address is the last. The calculator does this for you.
What does /24 mean?
The first 24 bits identify the network, leaving 8 bits for hosts. That gives 256 addresses, 254 of them usable, with mask 255.255.255.0.
Why are two addresses not usable?
In most subnets the lowest address is the network address and the highest is the broadcast address, so neither is assigned to a host.