CIDR Block Aggregator & Merger
Local ProcessingMerge overlapping and adjacent IPv4 CIDR blocks into the smallest possible set of aggregated subnets.
How It Works & Processing Standards
Merge overlapping and adjacent IPv4 CIDR blocks into the smallest possible set of aggregated subnets.
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Current Limits
- Maximum input length: 100,000 characters
Firewall rules and allow lists pile up overlapping, fragmented ranges over time. Enter one CIDR per line and the list shrinks while the covered addresses stay the same.
What You Can Do
- Join neighbours
- 192.168.0.0/24 + 192.168.1.0/24 → 192.168.0.0/23
- Remove overlaps
- Smaller ranges inside a larger one are dropped.
How to Use CIDR Block Aggregator & Merger
- 1Enter the CIDR listPaste one per line.
- 2CopyCopy the shorter list.
Examples
Two adjacent /24s
Input: 192.168.0.0/24
192.168.1.0/24
Result: 192.168.0.0/23
A contained range and a separate one
Input: 10.0.0.0/24
10.0.0.128/25
10.0.2.0/24
Result: 10.0.0.0/24
10.0.2.0/24
Common Use Cases
- Reducing the number of firewall or security-group rules
- Tidying IP allow lists gathered from several sources
Frequently Asked Questions (FAQ)
Why are 10.0.0.0/24 and 10.0.2.0/24 not merged?
10.0.1.0/24 lies between them, so merging would add addresses that were not there. Ranges are merged only when the covered addresses stay the same.