Subnet Mask Converter
Enter a subnet mask (e.g. 255.255.255.0) or CIDR prefix (e.g. /24) to convert between mask, CIDR, wildcard mask, and host count. All calculations happen inside your browser.
Enter a mask or CIDR to see the result.
0
CIDR prefix
-Subnet mask
-Wildcard mask
-Usable hosts
How to use
- Enter either a subnet mask or a CIDR prefix.
- The CIDR, mask, wildcard, and host count are calculated automatically.
- Use it for router ACLs or subnet design.
Frequently asked questions
What can I enter?
Enter any of a subnet mask (e.g. 255.255.255.0) or CIDR prefix (e.g. /24 or 24), and it converts to the other formats.
What is a wildcard mask?
A wildcard mask is the bitwise inverse of the subnet mask, used mainly in router ACLs. For example, the wildcard for 255.255.255.0 is 0.0.0.255.
Are the values I enter sent to a server?
No. All calculations happen only inside your browser, and the values you enter are never sent to or stored on any server.