TOOL 18 / BROWSER-SIDE
CIDR / Subnet Calculator
Calculate IPv4 network boundaries. No uploads, no backend.
FREE TO USE / NO ADS / NO LOGIN REQUIRED
Calculate an IPv4 subnet from CIDR notation
Enter an IPv4 address and prefix length to inspect its network boundary and address range. Useful when checking an allowlist, subnet or routing plan.
- Calculate IPv4 network boundaries
- Inspect the subnet address range
- Review CIDR prefix information
Enter an IPv4 CIDR block and run the calculation. Review the network and address range before copying values into a firewall or network configuration. This calculator covers IPv4 rather than IPv6.
Popular ways to use CIDR / Subnet Calculator
- Check the network boundary of an IPv4 CIDR block.
- Estimate the address range available to a subnet.
How processing and privacy work
Processing runs in your browser. The page may download scripts, fonts or processing engines to run the tool; these downloads are separate from uploading your input files.