IP address type checker: public or private
Useful when writing firewall rules or reading logs, to tell whether an address comes from the internet or an internal network.
Loading the tool…
Processing and privacy: The result is calculated inside your browser and your data is not sent to any server.
How to use it
- Enter ipv4 or ipv6 address.
- The result appears straight away and updates as you edit.
- Copy the result, or copy a link that keeps the same values to share it.
How it is calculated
The address is matched against the IANA special-purpose address registry (RFC 6890), most specific range first. Historic IPv4 class from the first octet: A 0 to 127, B 128 to 191, C 192 to 223, D 224 to 239, E 240 to 255.
Example
Inputs: IPv4 or IPv6 address = 192.168.1.20. Result: Address type: Private network; Version: IPv4; Reachable on the public internet: No.
192.168.1.20
192.168.0.0/16
Limits and caveats
- Based on the IANA special-purpose registry; it cannot tell the country or provider, which needs live data.
- A public address does not mean the host is reachable; a firewall may still block it.
Questions about this tool
Which IPv4 ranges are private?
10.0.0.0/8, 172.16.0.0/12 and 192.168.0.0/16, per RFC 1918.
What is the 100.64.x.x address on my router?
It is shared address space used by providers running carrier-grade NAT, not a public address.
Are classes A, B and C still used?
No. CIDR replaced them in 1993, though courses and exams still mention them.