Free network utility
IPv4 Subnet Calculator
Calculate network, broadcast, usable host range, netmask, and wildcard mask from IPv4 CIDR notation.
What this tool calculates
Calculate network, broadcast, usable host range, netmask, and wildcard mask from IPv4 CIDR notation. The calculation is designed for practical home and small-office network planning.
Important limitations
Results depend on the values and settings you provide. Verify changes with the router manufacturer, internet provider, or an authorized network administrator before applying them to an important network.
Privacy and responsible use
This calculation runs locally in your browser. RouterNAT does not receive or save the values entered into this tool. Use the result only for lawful network administration and troubleshooting.
Related RouterNAT guides
To understand WAN and public-address differences, read the complete CGNAT detection guide before changing NAT or port-forwarding settings.
How to use this result
Verify important changes against your router manual, ISP documentation, or an authorized network administrator. This utility provides planning guidance and does not connect to, scan, or modify your router.