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.
Why client-side?
Every byte you paste, type, or upload here is processed entirely inside your browser. Nothing is sent to a server, logged, or stored. That means it's safe to use this tool on production secrets, customer data, internal logs, and any input you would not paste into a hosted SaaS formatter.
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Frequently Asked Questions
- 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.