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Subnet Consolidation

Consolidate multiple contiguous subnets into one larger subnet

Subnets to Consolidate

How to use

About this tool

Consolidates multiple contiguous subnets (CIDR notation) into one larger subnet. Determines in real time whether consolidation is possible, and if so, displays the consolidated subnet, original subnet count, and saved address count. If consolidation is not possible, clearly displays the reason. All calculations are done in the browser.

How to use

Enter the subnets to consolidate in CIDR notation (e.g., 192.168.1.0/26), one per line. Results are displayed in real time as you type. If consolidation is possible: The consolidated subnet (CIDR notation), original subnet count, consolidated subnet count (always 1), and saved address count are displayed. If consolidation is not possible: A "Cannot Consolidate" message and reason (e.g., "Subnets are not contiguous") are displayed. You can copy the results.

Options

Subnets to consolidate: Enter CIDR notation (e.g., 192.168.1.0/26), one per line. Consolidation requirements: All subnets must have the same prefix length, be in the same network address space (first 3 octets must match), be contiguous, and the subnet count must be a power of two (2, 4, 8, 16, ...). Results: The consolidated subnet (CIDR notation), original subnet count, consolidated subnet count (always 1), and saved address count are displayed.

Use cases

β€’ Network design optimization (consolidating multiple small subnets into one to simplify management) β€’ Efficient use of network resources (removing unnecessary subnet boundaries to save address space) β€’ Network redesign (reviewing existing subnet configurations to identify consolidatable subnets) β€’ Network management (verifying and documenting consolidated subnet information) β€’ Router and switch configuration updates (updating settings based on consolidated subnet information)

How it works

Subnet consolidation determines whether multiple contiguous subnets can be consolidated and, if so, calculates the consolidated prefix length and network address. Consolidation checks: Verifies that all subnets have the same prefix length, are in the same network address space, are contiguous (previous subnet's broadcast address + 1 = next subnet's network address), and that the subnet count is a power of two. Consolidated prefix length calculation: consolidatedPrefix = originalPrefix - log2(subnetCount). Consolidated network address: The first subnet's network address. Saved address count calculation: Total addresses before consolidation - addresses after consolidation. All calculations are implemented with JavaScript bitwise operations and complete instantly in the browser.

Privacy and data

All calculations are done in the browser; no network information is sent to any server.

FAQ

Q: What conditions must be met to consolidate subnets?
A: All subnets must have the same prefix length, be in the same address space, be contiguous (each subnet's network address immediately follows the previous broadcast address), and the count must be a power of two (2, 4, 8, 16…).
Q: How is the consolidated prefix length calculated?
A: consolidatedPrefix = originalPrefix - log2(subnetCount). For example, consolidating four /26 subnets: /26 - log2(4) = /26 - 2 = /24.
Q: What does "saved address count" mean?
A: It shows the reduction in the number of individual subnet overhead addresses (network + broadcast) eliminated by consolidation. Fewer subnets means fewer network/broadcast addresses wasted on overhead.
Q: Why might consolidation fail even when subnets look contiguous?
A: Common reasons: subnet count is not a power of two, the subnets have different prefix lengths, or the starting network address is not on a natural boundary for the consolidated prefix (i.e. the first subnet's network address is not aligned to the new prefix length).
Q: Does this tool send my network data to a server?
A: No. All calculations are performed entirely in the browser. No network information is sent to any server.