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CIDR Calculator

Developer Tools

Calculate CIDR subnets

CIDR Notation192.168.1.0/24
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
Total Addresses256
Usable Hosts254
IP ClassC

About CIDR Calculator

Calculate IP ranges, subnet masks, and network info from CIDR notation.

Frequently Asked Questions

What is CIDR notation?
CIDR (Classless Inter-Domain Routing) notation is a compact way to specify an IP address and its associated network mask. For example, 192.168.1.0/24 means the first 24 bits are the network portion, leaving 8 bits for host addresses.
How do I calculate the number of usable hosts?
The total number of addresses in a subnet is 2 raised to the power of (32 minus the prefix length). Usable host addresses are two fewer, since the network address and broadcast address are reserved. For a /24 network, that is 254 usable hosts.
What is a wildcard mask?
A wildcard mask is the inverse of a subnet mask. Where the subnet mask has 1-bits, the wildcard mask has 0-bits, and vice versa. Wildcard masks are commonly used in access control lists on routers and firewalls.
Is my data safe?
Yes! All processing happens entirely in your browser. Your IP addresses and network data are never sent to any server. No data is collected, stored, or transmitted.
Does this support IPv6?
This tool currently supports IPv4 CIDR calculations only. IPv4 addresses use 32-bit notation (e.g., 192.168.1.0/24). IPv6 support may be added in a future update.
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