CIDR Calculator & Subnet Mask Online (Free)
Calculate subnet ranges, network addresses, and host counts from CIDR notation. Free, browser-based networking tool.
CIDR notation (e.g. 192.168.1.0/24) defines IP address ranges for cloud VPCs, office networks, and Docker containers. A calculator saves manual binary math when planning subnets.
What CIDR tells you
- Network address and broadcast address
- First and last usable host IPs
- Total number of host addresses
- Subnet mask in dotted decimal form