Convert IP ranges to CIDR blocks and CIDR blocks to IP ranges.
The CIDR calculator converts in both directions: a CIDR block such as 192.168.0.0/22 becomes its first and last IP address and number of addresses, and a range such as 10.0.0.5 - 10.0.0.20 becomes the smallest list of CIDR blocks that covers it exactly.
Paste many lines at once to build firewall rules, cloud security groups or allow lists.
The minimal set of blocks for any range.
First and last address and count.
Fixes blocks that don't start on a boundary.
Up to 500 lines.
An IP address and a prefix length, e.g. /24, that together describe a range of addresses.
A CIDR block always has a power-of-two size starting on a boundary, so most ranges need several.
Not yet, IPv4 only.