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CIDR and Netmask Converter

Convert an IPv4 prefix length into a dotted netmask and back.

Convert in your browser · No sign-up

Accepts prefixes 0–32. Reverse conversion rejects masks whose binary ones are not contiguous.

Up to 100,000 UTF-16 units per input and 1,000,000 per result. See the supported formats and examples below.

Result

Add your input or load an example, then run the tool. Your result will appear here.

How to use

  1. Convert an IPv4 prefix length into a dotted netmask and back.
  2. Choose the mode or options, then run the tool.
  3. Review the result, then copy or download the TXT file.

Example

/24 ⇄ 255.255.255.0

Details and limitations

Text stays in your browser; it is not sent to a conversion server.

Format references

Tool page updated: