Merge multiple CIDR blocks into supernets, deduplicate, and optimize routing tables
Zero Dependencies · Works OfflineThe IP CIDR Merger is a free online network tool that intelligently merges multiple CIDR blocks into larger supernets, automatically deduplicates overlapping blocks, and optimizes routing table entries. Ideal for network engineers performing route aggregation, firewall rule optimization, and IP address planning. All calculations run locally in your browser—no data is ever uploaded to a server.
1. Enter CIDR notation in the input box, e.g., 192.168.0.0/24, one per line.
2. Click "Merge" or use Ctrl+Enter.
3. View merge results and statistics.
4. Click "Copy Results" or download as CSV.
Network engineers need to aggregate smaller blocks into larger supernets in BGP/OSPF configurations to reduce routing table entries.
Security operators merge multiple CIDR rules into fewer supernet rules for improved firewall matching efficiency.
When configuring VPCs in AWS/Azure, verify whether multiple subnets can be aggregated into a larger address block.
CIDR merging (route aggregation/supernetting) is a fundamental network engineering operation. The core principle: when multiple contiguous CIDR blocks belong to the same larger supernet, a single supernet route can replace multiple subnet routes. For example, 192.168.0.0/24 and 192.168.1.0/24 can merge into 192.168.0.0/23. Merge conditions: blocks must be contiguous, have the same prefix length, and align on supernet boundaries. RFC 4632 defines CIDR specifications, and route aggregation is one of CIDR's core values.
CIDR merging combines multiple contiguous CIDR blocks into a larger supernet, reducing routing table entries.
Currently only IPv4 is supported. IPv6 support is planned for a future release.
The tool converts CIDRs to IP ranges, sorts and deduplicates, merges adjacent ranges, then converts back to CIDR notation.
No. All calculations run locally in your browser.
Yes. Enter one CIDR per line and the tool automatically deduplicates and merges.
The tool shows both before and after CIDR lists for easy comparison.