Define your network
Start with any IPv4 or IPv6 CIDR range and instantly see available host counts and address boundaries.
CIDR split assistant
Calculate IPv4 & IPv6 subnet plans and export results
Define the base IPv4 or IPv6 network, choose one or more split levels and visualise the resulting subnet tree with full address details.
Planner mode
Switch between IPv4 and IPv6 planners
Explore classic IPv4 splits or inspect IPv6 allocations without leaving the page.
Each planner keeps its own inputs so you can compare results back to back.
IPv4 Planner
Prepare your IPv4 split
Preview
Subnet breakdown
| Mask | Hosts | Actions |
|---|---|---|
| Click "Generate subnets" to start a calculation. | ||
How CIDR Splitter Works
Use the CIDR subnet calculator to plan efficient IPv4 and IPv6 allocations. Enter your base CIDR block, explore the splits, and export the structure your network team needs.
Split with precision
Choose target masks, split subnets in bulk, and visualise how each branch of the hierarchy expands.
Share the plan
Export the CIDR tree to reuse in documentation, change requests, or automation workflows.
Understand IPv6 notation
IPv6 uses 128-bit hexadecimal notation arranged into eight hextets. Collapse consecutive zero blocks with the double-colon (::) shortcut, drop leading zeros, and let the planner expand/recompress the address to confirm the canonical form.
Split IPv6 allocations
Start from a base allocation (for example /32) and choose a deeper prefix like /48 or /64. Each step consumes more network bits and leaves fewer host bits—CIDR Splitter calculates how many subnets and addresses each target tier unlocks.
CIDR Splitter Features
Focused on network architects, the tool highlights the insights that make CIDR / subnet planning faster and more reliable. Visualise the split results and share them with your team via CSV export.
Real-time subnet table
Inspect every subnet with live updates to masks, host counts, and CIDR notation.
Bulk operations
Calculate subnets faster by applying new subnet masks to multiple nodes simultaneously to test alternative capacity plans.
Export-ready outputs
Download structured data that fits easily into change control documentation, CSV imports, or audit reports.
Frequently Asked Questions
Understand the terminology and features that power the CIDR Splitter so you can plan subnets with confidence.