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CIDR to IP range

Enter a CIDR block to get its first and last address and how many addresses it holds. Paste a list to convert many at once.

One per line, or separated by commas. Netmasks work too: 10.0.0.0 255.255.0.0.

Try:

Range

203.0.113.64/26

Example: type your own block above.

First address203.0.113.64
Last address203.0.113.127
Addresses64
CIDR
203.0.113.64/26
Netmask
255.255.255.192
Wildcard mask
0.0.0.63

How it works

A CIDR block is an address followed by a prefix length, like 192.168.0.0/22. The prefix length says how many of the address's leading bits are fixed. The rest can be anything, so a block holds 2(32 − prefix) IPv4 addresses, or 2(128 − prefix) IPv6 addresses.

The first address has all the free bits set to 0, and the last has them all set to 1. For 192.168.0.0/22 that's 192.168.0.0 to 192.168.3.255: 1,024 addresses.

On an IPv4 LAN, the first address names the network and the last is the broadcast address, so hosts use the ones in between. Use the subnet calculator for usable hosts, netmasks and more. To go the other way, use IP range to CIDR.