What is a wildcard mask in networking?

A wildcard mask is the bitwise inverse of a subnet mask (e.g. a `255.255.255.0` netmask has a wildcard mask of `0.0.0.255`), used in Cisco router ACLs and OSPF network statements.

Updated: August 2026 • Verified v1.2

IPv4 CIDR to IP Range & Subnet Host Expander

Q: How many usable hosts are in a /24 subnet?

A `/24` subnet contains 256 total IP addresses, of which 254 are usable for host devices (reserving the network address `.0` and broadcast address `.255`).

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CIDR Bitmasking: Netmask = (~0 << (32 - Prefix)); Usable_Hosts = 2^(32 - Prefix) - 2

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Understanding Your Results

Calculates network address, broadcast address, first and last usable host IPs, total and usable host capacities, dotted-decimal subnet masks, and Cisco wildcard masks.

Practical Guidance & Next Steps

In standard IPv4 subnets (/30 and below), 2 IP addresses are reserved: the network address (first) and the broadcast address (last).

What is this?

A networking utility that translates IPv4 CIDR block notation into detailed subnet IP ranges and host capacities.

How does it work?

1. Enter any IPv4 CIDR notation (e.g. `192.168.1.0/24` or `10.0.0.0/16`). 2. View network address, broadcast address, first usable IP, last usable IP, and total host capacity. 3. Copy the subnet breakdown in 1 click.

Why use it?

Essential for setting up AWS VPCs, Azure VNets, Kubernetes pod CIDRs, and Cisco ACLs.

Technical Scope & Calculation Limitations

Calculates standard IPv4 CIDR blocks (prefix lengths /0 to /32).

Frequently Asked Questions

A `/24` subnet contains 256 total IP addresses, of which 254 are usable for host devices (reserving the network address `.0` and broadcast address `.255`).

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