Subnet Mask Calculator

Enter a /prefix or dotted-decimal subnet mask to get its matching CIDR, binary mask, wildcard mask, and address counts.

Prefix or subnet mask

Example IP (optional)

—CIDR prefix

—Subnet mask

—Wildcard mask

—Total addresses

ReadyConvert a dotted subnet mask or CIDR prefix.

How to use this Subnet Mask Calculator

Convert IPv4 CIDR prefixes and subnet masks in both directions. Enter your values above and the result is calculated directly in your browser. No account is required.

Fast answer, clear inputs

This tool is built around one job: give the answer quickly without forcing a signup or hiding the result. Related tools are linked nearby when the next calculation or conversion is useful.