CIDR to IP Range Converter: Network, Broadcast and Hosts

Convert CIDR notation into an IP range and back again, with the network address, broadcast address, subnet mask, wildcard mask, usable hosts and the exact CIDR blocks that cover any address range.

CIDR to IP range

IP range to CIDR blocks

IPv6 CIDR block

What the prefix length is doing

A subnet mask is just a prefix length written out in full. /24 is the same as 255.255.255.0, and /16 is 255.255.0.0. The prefix counts the network bits from the left; everything left over is the host part. Double the host bits and you double the addresses, which is why /25 holds 128 addresses and /23 holds 512.

Two prefixes are special. A /31 is a point-to-point link with two usable addresses and no reserved network or broadcast address, standardised in RFC 3021 for inter-router links. A /32 is a single host route pointing at one address. Both are correct answers here, not mistakes.

Turning an address range into CIDR blocks

Firewall rules, cloud security groups and access lists often want a single address range, but most ranges are not a clean CIDR block. A range such as 192.168.1.1 to 192.168.1.6 cannot be written as one prefix, so this tool splits it into the smallest possible set of aligned CIDR blocks that cover exactly that range and nothing else – here /32, /31, /31, /32.

The blocks are aligned because a valid CIDR block must start on a multiple of its own size. That is the whole reason a range expands into several entries, and why a tool that returns one wrong-looking prefix is usually returning a network address that has been silently rounded.

Reviewed and fact-checked on 28 September 2026.