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CIDR Calculator

Calculate subnet details from CIDR notation: network address, broadcast, host range, subnet mask, wildcard mask, and more.

Enter an IPv4 address, or include a prefix like 10.0.0.0/8

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Enter an IP address and click "Calculate" to see subnet details
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About CIDR Calculator

CIDR (Classless Inter-Domain Routing) is a method of allocating IP addresses and routing Internet Protocol packets that replaced the old classful addressing system. CIDR notation compactly represents an IP address and its associated network mask by appending a suffix indicating the number of leading bits in the mask, such as 192.168.1.0/24. Understanding CIDR is essential for network engineers, system administrators, and developers working with cloud infrastructure, VPCs, firewalls, and access control lists.

Our CIDR Calculator instantly computes all relevant subnet information from any IPv4 address and prefix length. It derives the network and broadcast addresses, the range of usable host IPs, subnet and wildcard masks, total and usable host counts, the IP class, and the binary representation of the subnet mask. All calculations run entirely in your browser using custom IP math logic with no external libraries or server requests, keeping your network data completely private.

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How to Use

01

Enter IP Address

Type an IPv4 address in the input field, either standalone (e.g., 10.0.0.0) or in CIDR notation (e.g., 10.0.0.0/8). You can also use the slider or dropdown to set the prefix length.

02

Calculate

Click "Calculate" or press Enter to compute the full subnet details. Use the preset buttons (/8, /16, /24, /28, /30, /32) for quick common configurations.

03

Review Results

View the results grid showing network address, broadcast address, host range, masks, host counts, IP class, and binary mask. Click any value to copy it to your clipboard.

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Frequently Asked Questions

What is a CIDR Calculator? expand_more
A CIDR Calculator is a networking tool that takes an IP address and a prefix length (e.g., /24) and computes detailed subnet information including the network address, broadcast address, usable host range, subnet mask, wildcard mask, and total number of hosts. It helps network engineers quickly plan and troubleshoot IP address allocations.
What does the prefix length (e.g., /24) mean? expand_more
The prefix length indicates how many of the 32 bits in an IPv4 address are used for the network portion. A /24 means the first 24 bits identify the network and the remaining 8 bits are available for host addresses, giving 256 total IPs (254 usable). A shorter prefix like /16 provides a larger network with more hosts, while a longer prefix like /30 creates a very small subnet.
What is the difference between subnet mask and wildcard mask? expand_more
A subnet mask marks which bits of an IP address belong to the network (1s) versus the host (0s). For example, /24 gives a subnet mask of 255.255.255.0. A wildcard mask is the bitwise inverse, swapping 1s and 0s (0.0.0.255 for /24). Wildcard masks are commonly used in Cisco ACLs and OSPF configurations to match ranges of addresses.
Is my network data sent to a server? expand_more
No. All calculations are performed entirely in your browser using JavaScript. No IP addresses or subnet information is transmitted to any server. Your network planning data remains completely private and secure on your device.