Subnet Mask Calculator
A free, browser-based calculator. Runs entirely in your browser — no sign up, nothing stored.
100% FreeRuns in your browserBasic
Enter Values
Enter your values and press Calculate to see results.
How to use this calculator
- Enter the CIDR prefix (0–32).
- Press Calculate for the subnet and wildcard masks.
How it works
The subnet mask is the network bits set to 1: a /24 is 255.255.255.0. The wildcard mask is its inverse (0.0.0.255), used in some ACLs and routing.
Worked example
/26. Mask 255.255.255.192, wildcard 0.0.0.63, 62 usable hosts.
Related tools
Tip: Enter any known values to calculate the remaining results.
All calculations run in your browser. Your inputs are never saved or transmitted.