Subnet Visualizer

Subnetting is the process of dividing a large IP network into smaller, more manageable sub-networks (subnets). It's crucial for: efficient IP address allocation, improving network performance by reducing broadcast domains, enhancing security through network isolation, and supporting routing decisions. Understanding subnetting is essential for CCNA, network administration, and cybersecurity roles.

CIDR (Classless Inter-Domain Routing) notation represents the subnet mask as a single number after a slash (e.g., /24). This number indicates how many bits are used for the network portion. For example, /24 equals 255.255.255.0 (24 ones followed by 8 zeros in binary). CIDR replaced classful networking, allowing more flexible IP address allocation. Our tool converts between CIDR and dotted-decimal mask notation automatically.

The formula is: Usable Hosts = 2^(host bits) - 2. Host bits = 32 - CIDR. For example, with /24: host bits = 32 - 24 = 8, so Total IPs = 2^8 = 256, and Usable Hosts = 256 - 2 = 254. We subtract 2 because the first IP is reserved for the Network Address and the last IP is reserved for the Broadcast Address. Our tool displays this calculation step-by-step.

The Network Address is the first IP in a subnet (all host bits = 0) and identifies the network itself—it cannot be assigned to a device. The Broadcast Address is the last IP in a subnet (all host bits = 1) and is used to send data to all devices on that subnet. Between these two are the usable host addresses that can be assigned to computers, servers, and other devices.

The Binary View displays your IP address, subnet mask, and network address in 32-bit binary format with color-coded highlighting. Green bits represent the network portion (determined by CIDR), while red bits represent the host portion. This visual representation is invaluable for understanding how the AND operation between IP and mask produces the network address—a core concept in networking exams like CCNA.

When you split a network (e.g., into 4 subnets), the tool "borrows" bits from the host portion. Splitting /24 into 4 subnets borrows 2 bits (since 2^2 = 4), creating four /26 subnets with 62 hosts each. The tool displays these as color-coded visual blocks showing each subnet's network address, broadcast address, usable range, and host count—making VLSM and subnetting calculations intuitive.

The Practice Mode generates random subnetting questions to test your knowledge. Choose your difficulty level (Easy, Medium, Hard) and number of questions. You'll be asked to calculate network addresses, broadcast addresses, usable hosts, and subnet masks—just like in CCNA, Network+, or IT certification exams. Instant feedback shows correct answers to help you learn from mistakes.

Yes! Our Class Comparison feature shows the difference between legacy classful networking (Class A/B/C with default masks of /8, /16, /24) and modern CIDR. While CIDR has largely replaced classful routing, understanding classes remains important for exams and legacy systems. The tool auto-detects the IP class and shows how many bits you've "borrowed" from the default class mask.

100% Private, No APIs. All subnet calculations happen locally in your browser using pure JavaScript. Your IP addresses are never sent to any server. The tool works entirely offline after the page loads—perfect for educational institutions, enterprise networks, or anyone who values privacy. No internet connection is required for calculations.

Yes! Our tool offers multiple export options: Copy to Clipboard for quick sharing, TXT download for documentation, and Print/PDF for creating reference sheets. When you've split a network into subnets, the export includes all subnet details with network addresses, ranges, broadcasts, and host counts—perfect for network planning documents.