A subnet (subnetwork) is a logical subdivision of an IP network. Subnetting divides a network into smaller segments for performance and security.

What is CIDR notation?

CIDR (Classless Inter-Domain Routing) notation uses a suffix like /24 to indicate how many bits of the IP address are used for the network portion. For example, /24 means the first 24 bits are the network and the last 8 are for hosts.

What is a wildcard mask?

A wildcard mask is the inverse of a subnet mask. It is commonly used in ACLs and OSPF configurations. For a /24 subnet, the wildcard mask is 0.0.0.255.

What is the broadcast address?

The broadcast address is the last address in a subnet. Packets sent to this address are delivered to all hosts on the subnet.

How many usable hosts in a /24?

A /24 subnet has 256 total addresses, minus 2 for the network and broadcast addresses, leaving 254 usable host addresses.

Subnet/CIDR Calculator

Enter an IP address and subnet mask to instantly view network address, broadcast, host range, wildcard mask, and total usable hosts.

IP Address

Enter a valid IPv4 address (e.g. 192.168.1.0).

CIDR / Subnet Mask

Subnet Details

/24

CIDR

254

Usable Hosts

256

Total Addresses

Calculated Results

Network Address192.168.1.0

Broadcast Address192.168.1.255

First Usable Host192.168.1.1

Last Usable Host192.168.1.254

Subnet Mask255.255.255.0

Wildcard Mask0.0.0.255

Binary Mask11111111.11111111.11111111.00000000

Documentation

How It Works

Enter an IPv4 address and select a CIDR prefix length. The calculator performs bitwise AND between the IP and subnet mask to find the Network Address, and OR with the wildcard mask to find the Broadcast Address.

Usable host addresses are all IPs between the network and broadcast addresses, exclusive (except for /31 point-to-point and /32 host routes).

Key Formulas

Network: IP AND Subnet Mask

Broadcast: Network OR Wildcard Mask

Wildcard: NOT Subnet Mask (bitwise inverse)

Usable Hosts: 2^(32 - CIDR) - 2

Last Updated: February 2026

Note: This calculator supports IPv4 only.

Frequently Asked Questions

How to Use

About the Subnet/CIDR Calculator

What it calculates

This subnet/cidr calculator helps with subnetting, bandwidth, DNS TTL, and other IT networking calculations. Calculate network address, broadcast, host range, wildcard mask from IP and subnet.

When to use it

Use for network planning, certification prep, and sysadmin troubleshooting.

Example

Adjust the inputs above to model your specific scenario with the Subnet/CIDR Calculator.

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Subnet/CIDR Calculator

Calculated Results

How It Works

Key Formulas

About the Subnet/CIDR Calculator

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