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Advanced CIDR Calculator & Subnet Visualizer

Professional-grade network calculator supporting IPv4 and IPv6. Features dual-stack logic, binary visualization, deep subnetting analysis, and hardware config exports for Cisco/Linux.

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Category Network Utilities
Network Configuration
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Configuration Export
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Network Address -
Broadcast Address -
Usable IP Range -
Total Hosts -
Wildcard Mask -
IP Class / Type -
Binary Visualization
IP Addr
Netmask
Network
Network Bits Host Bits
Subnet Breakdown (Next Level)
Network Range Broadcast
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About

Subnetting is the backbone of efficient network design, yet it remains one of the most error-prone tasks in systems engineering. A single bit flip in a mask calculation can isolate a subnet, overlap routes, or expose broadcast traffic to the wrong segment. This tool is designed to eliminate those risks by providing bit-perfect precision for both IPv4 and IPv6 architectures.

Unlike basic calculators that stop at the decimal representation, this engine visualizes the binary logic occurring at the packet level. It handles the 32-bit constraints of legacy infrastructure and the 128-bit complexity of modern addressing with equal depth. We incorporate RFC 1918 compliance checks, Reserved bogon detection, and granular host range boundaries to ensure your configurations are production-ready before deployment.

cidr subnetting ipv6 network-engineering ip-calculator

Formulas

The core logic of subnetting relies on bitwise operations against the IP address binary string and the Subnet Mask.

{
Network = IP & MaskBroadcast = IP | ¬MaskHosts = 232-CIDR − 2

Where IP is the 32-bit integer of the address, Mask is the subnet mask derived from the CIDR prefix, and ¬ represents the bitwise NOT (inversion) operator used to calculate the Wildcard.

Reference Data

CIDRSubnet MaskWildcard MaskTotal AddressesUsable Hosts
/32255.255.255.2550.0.0.011 (Host Route)
/31255.255.255.2540.0.0.122 (PtP Links)
/30255.255.255.2520.0.0.342
/29255.255.255.2480.0.0.786
/28255.255.255.2400.0.0.151614
/27255.255.255.2240.0.0.313230
/26255.255.255.1920.0.0.636462
/25255.255.255.1280.0.0.127128126
/24255.255.255.00.0.0.255256254
/23255.255.254.00.0.1.255512510
/22255.255.252.00.0.3.2551,0241,022
/21255.255.248.00.0.7.2552,0482,046
/20255.255.240.00.0.15.2554,0964,094
/19255.255.224.00.0.31.2558,1928,190
/18255.255.192.00.0.63.25516,38416,382
/17255.255.128.00.0.127.25532,76832,766
/16255.255.0.00.0.255.25565,53665,534
/12255.240.0.00.15.255.2551,048,5761,048,574
/8255.0.0.00.255.255.25516,777,21616,777,214
/00.0.0.0255.255.255.2554,294,967,2964,294,967,294

Frequently Asked Questions

The Network Address (first IP in the block) is reserved to identify the subnet itself within routing tables. The Broadcast Address (last IP in the block) is reserved for communicating with all hosts in that subnet. Therefore, the usable range is (Network + 1) to (Broadcast - 1).
A /32 prefix represents a single IP address (Host Route) with 0 usable hosts. A /31 prefix is a special case used for Point-to-Point links (RFC 3021), where the Network and Broadcast addresses are used as the two usable endpoints, effectively giving 2 usable hosts despite the formula 2^n - 2 typically yielding 0.
IPv6 addresses are 128-bit, providing a vastly larger address space. Unlike IPv4, IPv6 does not use Broadcast addresses; it uses Multicast groups. Additionally, the standard subnet size for a LAN in IPv6 is almost exclusively /64, making variable length subnetting (VLSM) less common for end-user networks but critical for ISP allocations.
The Wildcard Mask is the inverse of the Subnet Mask. It is primarily used in Access Control Lists (ACLs) on Cisco devices and OSPF configurations to define which bits of an IP address must match. A "0" bit means "must match", while a "1" bit means "ignore".