IPv6 Subnet Planner

About This Tool

Hierarchically divide IPv6 address space for network planning and documentation.

Key Features:

• Nibble-Aligned Splitting: Click the green "Split" button to divide a network into smaller subnets at 4-bit boundaries (/20, /24, /28, etc.), creating 16 child subnets per split.
• Join Subnets: Click the red "Join" button to merge subnets back together into their parent network.
• Prefix Range: /16 to /64, with /64 as the minimum assignable subnet.
• Location-Based Planning: Shows count of /48s (typical site/location size) for prefixes < /48, and /64s (minimum subnet size) for prefixes ≥ /48.
• Visual Hierarchy: Join buttons span multiple rows to show parent-child relationships.
• Annotations: Add notes and color-code subnets for documentation.
• Shareable URLs: Complete state encoded in URL for easy sharing.

This tool was made by Jason Tally with the help of opencode.ai and Claude. The code is available on GitHub.

Credits

This IPv6 Subnet Planner was inspired by:

• Caesar Kabalan's IPv4 Visual Subnet Calculator
• davidc's original IPv4 subnet calculator