CIDR / Subnet Calculator
Calculate network details from CIDR notation. All calculations run entirely in your browser.
About the CIDR / Subnet Calculator — IP Network Calculator
Calculate subnet masks, network addresses, broadcast addresses, and usable host ranges from CIDR notation. Free, client-side IP subnet calculator for network engineers and developers.
Private by design
Everything you type here is processed inside your browser. Nothing is sent to a server, logged or stored, so it is safe to use with real numbers, drafts and anything you would not paste into a hosted tool.
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Questions people ask
What is CIDR notation?
CIDR (Classless Inter-Domain Routing) notation combines an IP address with a prefix length (e.g., 192.168.1.0/24) to define a network range. The prefix length indicates how many bits are used for the network portion.
How do I calculate a subnet?
Enter an IP address with CIDR prefix (e.g., 10.0.0.0/16) and the tool instantly calculates the network address, broadcast address, subnet mask, usable host range, and total hosts.
What is the difference between /24 and /16?
A /24 network has 256 total addresses (254 usable hosts), while a /16 network has 65,536 total addresses (65,534 usable hosts). The smaller the prefix number, the larger the network.
Is this subnet calculator free?
Yes. All calculations happen locally in your browser using standard IP math. No data is sent to any server.