CIDR Calculator

CIDR (Classless Inter-Domain Routing) notation is a compact method for specifying IP address ranges and subnets. Instead of using separate network and subnet mask fields, CIDR uses a single notation like 10.0.0.0/16 where the number after the slash indicates how many bits are used for the network prefix.

This calculator computes all essential network details from a given CIDR notation or IP range: network address, broadcast address, subnet mask, wildcard mask, usable host range, total number of hosts, and usable hosts. It also provides a binary visualization that helps you understand the bit-level structure of the subnet, and a subnet breakdown feature for dividing large networks into smaller subnets.

Common use cases include network planning and subnet design, calculating address ranges for firewall rules and security groups, understanding IP allocation in cloud environments (AWS VPCs, GCP subnets, Azure virtual networks), validating network configurations, and learning how IP subnetting works at the binary level.

1. Enter a CIDR or IP range — Type a CIDR notation such as 192.168.1.0/24 or use the example buttons to load common prefixes.
2. Optional subnet breakdown — Select a prefix from the dropdown to break down the network into smaller subnets (e.g., break a /16 into /24 subnets).
3. Click Calculate — The tool instantly computes all network details and displays them in summary cards.
4. Review results — Check network address, broadcast address, subnet mask, wildcard mask, host range, total hosts, and usable hosts.
5. Binary visualization — View the bit-level representation of the network and host portions to understand how the subnet is structured.
6. Subnet breakdown — If you selected a breakdown prefix, scroll through the list of all resulting subnets with their ranges and host counts.