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IPv4 Wildcard Mask Calculator

Calculate an IPv4 wildcard mask from a subnet mask or CIDR prefix. View the network and broadcast addresses, binary representations, and sample Cisco ACL and OSPF configuration statements.

Calculate a Wildcard Mask

Enter an IPv4 address and either a CIDR prefix (/24) or a dotted subnet mask (255.255.255.0).

Common Wildcard Mask Examples

CIDR	Subnet mask	Wildcard mask	Total addresses
/8	255.0.0.0	0.255.255.255	16,777,216
/16	255.255.0.0	0.0.255.255	65,536
/24	255.255.255.0	0.0.0.255	256
/25	255.255.255.128	0.0.0.127	128
/26	255.255.255.192	0.0.0.63	64
/27	255.255.255.224	0.0.0.31	32
/30	255.255.255.252	0.0.0.3	4
/32	255.255.255.255	0.0.0.0	1

Frequently Asked Questions

What is a wildcard mask?

A wildcard mask identifies which IPv4 address bits a networking configuration should match. It is commonly used in Cisco ACLs and routing protocol network statements.

What is the wildcard mask for /24?

The wildcard mask is 0.0.0.255, corresponding to subnet mask 255.255.255.0.

Can I enter a dotted subnet mask?

Yes. Enter a mask such as 255.255.255.192 or a CIDR prefix such as /26.

Why are there 256 addresses in a /24?

An IPv4 /24 leaves eight host bits. There are 2⁸ = 256 total addresses in that block.