Calculator
Example Data Table
| Input | Meaning | Expected Aggregation |
|---|---|---|
| 192.168.0.0/25 and 192.168.0.128/25 | Two adjacent half blocks | 192.168.0.0/24 |
| 10.10.0.0/24 and 10.10.1.0/24 | Two nearby private networks | 10.10.0.0/23 |
| 172.16.5.10-172.16.5.90 | Custom IP range | Minimal CIDR list |
| 203.0.113.5 | Single host address | 203.0.113.5/32 |
Formula Used
The calculator converts each IPv4 address into a 32-bit integer. It then sorts all ranges by start address.
Block size: 2 ^ (32 - prefix)
Subnet mask: 2^32 - block size
Network address: IP address AND subnet mask
Broadcast address: network address + block size - 1
Wildcard mask: 2 ^ (32 - prefix) - 1
Merge rule: merge when next start is less than or equal to current end plus one.
CIDR conversion: each merged range is split into the largest aligned power-of-two blocks.
How to Use This Calculator
Enter IPv4 CIDR blocks, single IP addresses, or IP ranges. Put each value on a new line for clear input.
Enable adjacent merging when you want the smallest routing table. Enable binary output when you need bit-level review.
Click Calculate to view results above the form. Use CSV for spreadsheets. Use PDF for quick reports.
IP Address Aggregation Guide
Purpose
IP address aggregation reduces many IPv4 routes into fewer CIDR blocks. It is useful when networks grow, move, or overlap. A clean aggregate can simplify routing tables. It can also make firewall rules easier to audit. This calculator accepts CIDR blocks, ranges, and single host addresses. It then creates a minimal set of CIDR results.
Why Aggregation Matters
Routers perform best when route lists stay controlled. Large tables can be harder to read. They may also cause mistakes during changes. Aggregation groups continuous address space under a shorter prefix. For example, two adjacent /25 blocks can become one /24 block. That single route covers the same addresses with less clutter.
Range Handling
The tool first converts addresses into numbers. This makes sorting and comparison reliable. Overlapping blocks are merged. Duplicate space is counted. Adjacent ranges can also be merged when the option is enabled. After merging, the calculator converts each continuous range back into CIDR notation. It always uses aligned network boundaries.
Advanced Review
The result table shows the start address, end address, prefix, subnet mask, wildcard mask, total addresses, usable hosts, and scope. Scope labels help separate public, private, loopback, multicast, and reserved space. Binary output is optional. It is helpful when checking prefix boundaries or teaching subnet logic.
Planning Notes
Aggregation should match real network ownership. Do not advertise a broad route unless every address inside it belongs to your design. A larger aggregate may accidentally include unused or external space. Always compare the calculated block with routing policy, firewall rules, NAT plans, and documentation.
Export Use
CSV export is best for spreadsheets and inventory systems. PDF export is better for review notes and change tickets. Keep both files with your network records. They can support audits, migrations, and troubleshooting. Review invalid entries before using the report. Clean input produces safer routing decisions.
FAQs
What is IP address aggregation?
It is the process of combining continuous IP ranges into fewer CIDR blocks. This helps reduce routing table size and improves network documentation.
Does this calculator support IPv6?
This version focuses on IPv4. IPv6 aggregation needs larger integer handling and a separate parsing method for 128-bit addresses.
Can I enter a single IP address?
Yes. A single IPv4 address is treated as a /32 host route. It appears as one exact CIDR block.
What does merge adjacent ranges mean?
It allows two touching ranges to become one continuous range. This can produce fewer CIDR blocks when boundaries align correctly.
What is a wildcard mask?
A wildcard mask is the inverse of a subnet mask. It is often used in routing filters, access lists, and network matching rules.
Why are duplicate addresses shown?
Duplicate addresses appear when input blocks overlap. The calculator counts them so you can see how much repeated address space was removed.
What does route reduction mean?
Route reduction compares valid input entries with final aggregated CIDR blocks. A higher value means the output is simpler than the input.
Should I always use the largest aggregate?
No. Use only aggregates that match your ownership, routing policy, and firewall design. Overly broad routes can include unwanted address space.