Network · Developer
Is this IP private or public?
Paste an IPv4 or IPv6 address. You get its type (private, CGNAT, loopback, link-local, documentation, multicast, reserved or public), the IANA block it falls in, and whether that block is globally reachable. Nothing is sent anywhere.
Inputs
Result
Enter an address, then press Check.
How it's checked
The address is parsed, then compared bit by bit against every block in the IANA special-purpose address registries, and the longest matching prefix wins (so 192.0.0.9 matches its own /32 rather than the wider 192.0.0.0/24). If nothing matches, an IPv4 address is public; an IPv6 address is public only if it sits inside 2000::/3, the Global Unicast range, and otherwise it is reserved by the IETF. The “reachable from the internet?” answer is the registry's own Globally Reachable column: Yes, No, or N/A where the registry gives no value.
Private means RFC 1918 (10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16) or the IPv6 Unique-Local block fc00::/7. CGNAT is the Shared Address Space 100.64.0.0/10 from RFC 6598, used by carriers between you and their NAT; it is not RFC 1918 private space, but it is not globally reachable either. If your router shows a WAN address in 100.64.0.0/10, your provider is doing carrier-grade NAT and inbound port forwarding will not work from the internet.
Quick range table
| Block | Type | Source | Reachable from the internet? |
|---|---|---|---|
10.0.0.0/8 | Private-Use | RFC 1918 | No |
172.16.0.0/12 | Private-Use | RFC 1918 | No |
192.168.0.0/16 | Private-Use | RFC 1918 | No |
100.64.0.0/10 | Shared Address Space (carrier-grade NAT) | RFC 6598 | No |
169.254.0.0/16 | Link Local | RFC 3927 | No |
127.0.0.0/8 | Loopback | RFC 1122 s3.2.1.3 | No |
192.0.2.0/24 | Documentation (TEST-NET-1) | RFC 5737 | No |
198.51.100.0/24 | Documentation (TEST-NET-2) | RFC 5737 | No |
203.0.113.0/24 | Documentation (TEST-NET-3) | RFC 5737 | No |
224.0.0.0/4 | Multicast (IANA multicast address space, not in the special-purpose registry) | IANA multicast-addresses | N/A |
240.0.0.0/4 | Reserved | RFC 1112 s4 | No |
Multicast (224.0.0.0/4 and ff00::/8) is assigned in IANA's multicast registries, not in the special-purpose registries, so the registry has no globally-reachable value for it and the table says N/A.
Full IPv4 special-purpose registry
| Block | Name | Source | Globally reachable |
|---|---|---|---|
0.0.0.0/8 | "This network" | RFC 791 s3.2 | No |
0.0.0.0/32 | "This host on this network" | RFC 1122 s3.2.1.3 | No |
10.0.0.0/8 | Private-Use | RFC 1918 | No |
100.64.0.0/10 | Shared Address Space (carrier-grade NAT) | RFC 6598 | No |
127.0.0.0/8 | Loopback | RFC 1122 s3.2.1.3 | No |
169.254.0.0/16 | Link Local | RFC 3927 | No |
172.16.0.0/12 | Private-Use | RFC 1918 | No |
192.0.0.0/24 | IETF Protocol Assignments | RFC 6890 s2.1 | No |
192.0.0.0/29 | IPv4 Service Continuity Prefix | RFC 7335 | No |
192.0.0.8/32 | IPv4 dummy address | RFC 7600 | No |
192.0.0.9/32 | Port Control Protocol Anycast | RFC 7723 | Yes |
192.0.0.10/32 | Traversal Using Relays around NAT Anycast | RFC 8155 | Yes |
192.0.0.170/32 | NAT64/DNS64 Discovery | RFC 8880, RFC 7050 | No |
192.0.0.171/32 | NAT64/DNS64 Discovery | RFC 8880, RFC 7050 | No |
192.0.2.0/24 | Documentation (TEST-NET-1) | RFC 5737 | No |
192.31.196.0/24 | AS112-v4 | RFC 7535 | Yes |
192.52.193.0/24 | AMT | RFC 7450 | Yes |
192.88.99.0/24 | Deprecated (6to4 Relay Anycast, terminated 2015-03) | RFC 7526 | N/A |
192.88.99.2/32 | 6a44-relay anycast address | RFC 6751 | No |
192.168.0.0/16 | Private-Use | RFC 1918 | No |
192.175.48.0/24 | Direct Delegation AS112 Service | RFC 7534 | Yes |
198.18.0.0/15 | Benchmarking | RFC 2544 | No |
198.51.100.0/24 | Documentation (TEST-NET-2) | RFC 5737 | No |
203.0.113.0/24 | Documentation (TEST-NET-3) | RFC 5737 | No |
224.0.0.0/4 | Multicast (IANA multicast address space, not in the special-purpose registry) | IANA multicast-addresses | N/A |
240.0.0.0/4 | Reserved | RFC 1112 s4 | No |
255.255.255.255/32 | Limited Broadcast | RFC 8190, RFC 919 s7 | No |
Full IPv6 special-purpose registry
| Block | Name | Source | Globally reachable |
|---|---|---|---|
::1/128 | Loopback Address | RFC 4291 | No |
::/128 | Unspecified Address | RFC 4291 | No |
::ffff:0:0/96 | IPv4-mapped Address | RFC 4291 | No |
64:ff9b::/96 | IPv4-IPv6 Translation | RFC 6052 | Yes |
64:ff9b:1::/48 | IPv4-IPv6 Translation (local-use) | RFC 8215 | No |
100::/64 | Discard-Only Address Block | RFC 6666 | No |
100:0:0:1::/64 | Dummy IPv6 Prefix | RFC 9780 | No |
2001::/23 | IETF Protocol Assignments | RFC 2928 | No |
2001::/32 | TEREDO | RFC 4380, RFC 8190 | N/A |
2001:1::1/128 | Port Control Protocol Anycast | RFC 7723 | Yes |
2001:1::2/128 | Traversal Using Relays around NAT Anycast | RFC 8155 | Yes |
2001:1::3/128 | DNS-SD Service Registration Protocol Anycast | RFC 9665 | Yes |
2001:2::/48 | Benchmarking | RFC 5180 | No |
2001:3::/32 | AMT | RFC 7450 | Yes |
2001:4:112::/48 | AS112-v6 | RFC 7535 | Yes |
2001:10::/28 | Deprecated (previously ORCHID, terminated 2014-03) | RFC 4843 | N/A |
2001:20::/28 | ORCHIDv2 | RFC 7343 | Yes |
2001:30::/28 | Drone Remote ID Protocol Entity Tags (DETs) Prefix | RFC 9374 | Yes |
2001:db8::/32 | Documentation | RFC 3849 | No |
2002::/16 | 6to4 | RFC 3056 | N/A |
2620:4f:8000::/48 | Direct Delegation AS112 Service | RFC 7534 | Yes |
3fff::/20 | Documentation | RFC 9637 | No |
5f00::/16 | Segment Routing (SRv6) SIDs | RFC 9602 | No |
fc00::/7 | Unique-Local | RFC 4193, RFC 8190 | No |
fe80::/10 | Link-Local Unicast | RFC 4291 | No |
ff00::/8 | Multicast (IANA IPv6 address space, not in the special-purpose registry) | RFC 4291 | N/A |
Sources, read 2026-09-30: IANA IPv4 Special-Purpose Address Registry and IPv6 Special-Purpose Address Registry (both last updated 2025-10-09); IANA IPv6 Address Space (last updated 2025-10-23); IANA IPv4 Multicast Address Space (last updated 2026-08-20). The registries change occasionally, so treat this page as a snapshot of those dates. For the addresses themselves, see what is my IP and the subnet calculator.
Frequently asked questions
What are the private IP address ranges?
For IPv4, RFC 1918 defines 10.0.0.0/8, 172.16.0.0/12 (172.16.0.0 to 172.31.255.255) and 192.168.0.0/16. For IPv6, the Unique-Local block is fc00::/7 (RFC 4193). None of these is globally reachable.
What is the CGNAT IP range?
100.64.0.0/10, the Shared Address Space from RFC 6598 (100.64.0.0 to 100.127.255.255). Carriers use it for carrier-grade NAT. It is forwardable inside a provider's network but not globally reachable.
Does “public” mean the address is in use?
No. It only means the address is outside every special-purpose block. The tool cannot tell whether the address is assigned, routed, or answering, because it makes no network calls.
Why is 169.254.x.x not private?
169.254.0.0/16 is Link Local (RFC 3927), used when DHCP fails. The registry marks it as not forwardable and not globally reachable, so it never crosses a router, which is stricter than RFC 1918 space.
Where do I find my own IP address?
Use the What Is My IP Address? page, then paste the result here. For where an IP is located rather than what kind it is, use the IP lookup tool.
Registry snapshot — no network access
Everything is computed in your browser from a copy of the IANA registries dated above. The result describes the address block, not any particular device or whether the address is currently assigned.