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CIDR Prefix to Subnet Mask

Use this online cidr prefix to subnet mask with pasted values. IPv4 only; /0 is 0.0.0.0 and /32 is 255.255.255.255.

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  1. 01

    Add your input

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  2. 02

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  3. 03

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slash notation to netmask online

Use cidr prefix to subnet mask online to work with your own network values. IPv4 only; /0 is 0.0.0.0 and /32 is 255.255.255.255.

How to use it

Enter IPv4 prefix (bits). Select Calculate, check the result units, then copy or download the JSON result.

Options and example settings

OptionChoices / valueExample default
IPv4 prefix (bits)Main input. Whole number. Zero or positive values. Maximum 32.24

Calculation method

mask = 2³² − 2^(32−prefix)

Worked examples

Worked case for cidr prefix to subnet mask. IPv4 only; /0 is 0.0.0.0 and /32 is 255.255.255.255.

CIDR Prefix to Subnet Mask — example with explicit inputs

Settings: No extra options

Input:

24

Expected result for the example input and options:

Output:

{
  "subnet_mask": "255.255.255.0",
  "wildcard_mask": "0.0.0.255"
}

Limitations and common mistakes

  • IPv4 only; /0 is 0.0.0.0 and /32 is 255.255.255.255.
  • Match every input to its displayed unit; scientific notation such as 1e-6 is accepted.

Frequently asked questions

How can I use slash notation to netmask online?

Enter IPv4 prefix (bits). Select Calculate, check the result units, then copy or download the JSON result.

Which model does CIDR Prefix to Subnet Mask use?

mask = 2³² − 2^(32−prefix). IPv4 only; /0 is 0.0.0.0 and /32 is 255.255.255.255.

Technical references

Where is my input processed?

The bundled tool processes input in your browser. It does not upload tool input to a conversion service. Other site plugins, analytics, advertising and browser extensions may have separate behavior.

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