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.
Practical example and verification criteria
IP Range to CIDR Converter: Distinguish IPv4 from IPv6 and select exactly the input the page accepts: an address, CIDR prefix, netmask, or start/end range. Each IPv4 octet must be 0–255 and a prefix must fit the address family's bit range. For host counts, first check the rules for including network and broadcast addresses.
IP Range to CIDR Converter: For a quick check, start with 192.168.1.0–192.168.1.255 → /24 as a small input whose result relationship you can verify directly. Confirm that the input summary, units, and options match your intent before applying the tool to real values or a copy of the source; this reduces setup mistakes.
IP Range to CIDR Converter: Split the address at binary boundaries and verify that the first and last network addresses, membership result, and total address count agree. Feed a conversion result into the reverse tool to see whether the original is recovered. Remember that a calculation does not change router, VLAN, or firewall settings or guarantee the current route.
IP Range to CIDR Converter · Work record: For real work, record the input conditions, selected options, and result together. Do not assume the same state will remain after a refresh or device change. Preserve important results separately using copy, download, a screenshot, or another method the page supports, then reopen them in the target environment.
IP Range to CIDR Converter · Error check: If an error or unexpected result appears, reduce the input, run again with default options, and then change one condition at a time. Recording error messages and boundary values helps distinguish format issues, unsupported cases, and browser resource limits, and prevents an empty result from being mistaken for success.
IP Range to CIDR Converter · Scope of use: Check the page guidance for browser processing versus server lookup, storage location, and supported scope. Use sensitive source material or secrets only when strictly necessary. High-impact work such as legal, financial, or medical decisions or changes to an operational system requires current authoritative information and a separate verification process.