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IPv4 Netmask Converter

Convert between CIDR prefix length, dotted subnet mask, wildcard mask, and hex — with address and usable-host counts.

This tool handles input and primary processing in your browser and is designed not to send the input to QuickKit’s server.

Netmask forms

Equivalent netmask representations
Prefix length
CIDR suffix
Subnet mask
Subnet mask (hex)
Subnet mask (binary)
Wildcard mask
Wildcard mask (hex)
Total addresses
Usable hosts
How it works

Enter any one of: a prefix length (24 or /24), a dotted subnet mask (255.255.255.0), or a wildcard mask (0.0.0.255). Usable-host count follows the common convention: prefix ≤ /30 subtracts the network and broadcast addresses, /31 has 2 usable addresses per RFC 3021, and /32 is a single host. A dotted mask that is valid both ways — only 0.0.0.0 and 255.255.255.255 — is read as a subnet mask, so 0.0.0.0 is /0 and 255.255.255.255 is /32; write the prefix length to state the other reading.