IP Range to CIDR Converter
Local ProcessingConvert start and end IPv4 address ranges into the minimal set of covering CIDR blocks.
How It Works & Processing Standards
Convert start and end IPv4 address ranges into the minimal set of covering CIDR blocks.
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Current Limits
- Maximum input length: 100,000 characters
A range that does not fall on power-of-two boundaries cannot be a single CIDR. This tool splits it into CIDRs with no gaps and no overlap.
What You Can Do
- Minimal blocks
- The fewest CIDRs that exactly cover the range.
- Exact boundaries
- No address outside the range is included.
How to Use IP Range to CIDR Converter
- 1Enter start and end IPThe first and last address of the range.
- 2CopyCopy the CIDRs, one per line.
Examples
An aligned range
Input: 192.168.1.0 – 192.168.1.255
Result: 192.168.1.0/24
A misaligned range
Input: 10.0.0.5 – 10.0.0.20
Result: 10.0.0.5/32, 10.0.0.6/31, 10.0.0.8/29, 10.0.0.16/30, 10.0.0.20/32
Common Use Cases
- Turning a "from X to Y" IP range into firewall or ACL rules
- Converting country or organisation IP range tables into CIDR lists
Frequently Asked Questions (FAQ)
Why do I get several CIDRs?
A CIDR block has a power-of-two size and must start on a multiple of that size. Ranges that do not fit must be split into several blocks.