🌐 Subnet Calculator

A subnet calculator is a tool that helps network administrators calculate IP address ranges, subnet masks, and network information for IPv4 and IPv6 networks. It simplifies the process of subnetting by automatically computing network addresses, broadcast addresses, and available host ranges.

CIDR (Classless Inter-Domain Routing) notation is a method of representing IP addresses and their associated network masks. It uses a slash followed by a number (e.g., /24) to indicate how many bits are used for the network portion of the address. For example, 192.168.1.0/24 means the first 24 bits represent the network.

Use the formula: 2^h - 2, where 'h' is the number of host bits (zeros in the subnet mask). The subtraction of 2 accounts for the network address and broadcast address, which cannot be assigned to hosts.

A subnet mask uses 1s to represent network bits and 0s for host bits, while a wildcard mask is the inverse - using 0s for network bits and 1s for host bits. Wildcard masks are commonly used in Access Control Lists (ACLs) and routing protocols.

The number of subnets depends on how many bits you borrow from the host portion. Use the formula: 2^s, where 's' is the number of subnet bits borrowed. For example, borrowing 3 bits gives you 2^3 = 8 subnets.

These are traditional classful network categories: Class A (1-126, /8 default), Class B (128-191, /16 default), and Class C (192-223, /24 default). Modern networks use classless addressing (CIDR) for more flexible allocation.

Yes, IPv6 subnetting works similarly to IPv4 but uses 128-bit addresses instead of 32-bit. Common IPv6 subnet boundaries are /64 for end networks and /48 or /56 for site allocations.

VLSM allows you to use different subnet mask lengths within the same network, enabling more efficient use of IP address space by allocating appropriately sized subnets for different network segments.