IP Range to CIDR Converter
Enter the start IP and end IP to calculate the minimal list of CIDR blocks that exactly cover the range. Handy for firewall and routing setup — all calculations happen inside your browser.
Enter the start IP and end IP to see the CIDR list.
How to use
- Enter the start IP and end IP.
- The minimal list of CIDR blocks covering the range is calculated automatically.
- Copy the CIDR list with "Copy result" and use it.
Frequently asked questions
Why are multiple CIDRs returned?
An arbitrary IP range often does not map cleanly to a single CIDR, so it is split into the smallest number of CIDR blocks that exactly cover the range.
Does the start/end order matter?
Yes. Even if the start IP is greater than the end IP, the two values are sorted automatically.
Are the values I enter sent to a server?
No. All calculations happen only inside your browser, and the values you enter are never sent to or stored on any server.