Wildcard Mask Converter

Convert freely between CIDR prefix, subnet mask and wildcard mask.

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CIDR, subnet mask or wildcard mask

Enter any one of a CIDR prefix, a subnet mask, or a wildcard mask.

About this tool

Enter a CIDR prefix, a subnet mask or a wildcard mask and instantly see all three equivalent forms. The conversion happens locally in your browser.

What input formats are accepted?

A CIDR like /24, a subnet mask like 255.255.255.0, or a wildcard mask like 0.0.0.255 — it detects which one you entered.

What is a wildcard mask used for?

It is the inverse of a subnet mask and is used in access control lists and OSPF to match ranges of addresses.