Convert tools

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.

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

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

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

FAQ

CIDR and Netmask Converter — What are the supported inputs and limits?

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

Format references

Tool page updated: