Subnet Mask Converter
Turn a CIDR prefix into mask, wildcard, and host count.
One prefix, every form
A CIDR prefix like /24 is compact, but you often need the same information in other forms — the dotted mask, the wildcard, the host count. This converter produces them all from the prefix.
A /24 becomes 255.255.255.0, a wildcard of 0.0.0.255, 256 total addresses, and 254 usable hosts. The 32-bit binary makes the network boundary obvious at a glance.
Complete and private
The conversion runs in your browser, so nothing you enter is uploaded.
Frequently Asked Questions
What does it convert?
A prefix length from 0 to 32 into the dotted-decimal subnet mask, the wildcard mask, the total addresses, and usable hosts.
How many usable hosts?
Total addresses minus two for the network and broadcast, for prefixes up to /30. A /31 and /32 are special cases for point-to-point and single hosts.
Does it show binary?
Yes. The 32-bit binary form of the mask is included so you can see exactly where the boundary falls.
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