IP Class Checker
Enter an IP address to check its A–E class, whether it is private or public, and special uses such as loopback, link-local, and multicast. All calculations happen inside your browser.
Enter an IP address to see the result.
How to use
- Enter the IP address to check.
- The class (A–E) and private/public/special use are determined automatically.
- You can also check the default subnet mask for each class.
Frequently asked questions
What is the difference between a private and public IP?
Private IPs are used only inside internal networks — the 10.x, 172.16–31.x, and 192.168.x ranges. Public IPs are uniquely identified on the internet.
How are IP classes divided?
By the first octet: A (1–126), B (128–191), C (192–223), D (224–239, multicast), E (240–255, reserved). 127 is loopback.
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 Class Checker: 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 Class Checker: For a quick check, start with 10.0.0.1 → Class A / private 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 Class Checker: 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 Class Checker · 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 Class Checker · 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 Class Checker · 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.