A public IP is the address the open internet uses to reach your connection. A private IP is only for your local network (home Wi‑Fi, office LAN). Your laptop may show 192.168.1.20 while FindMyIP shows a different number — both can be correct. One is local; the other is what websites see.
Check the public side on What Is My IP, then look up any address with IP Lookup.
The short distinction
- Private IP — works inside your LAN / Wi‑Fi; assigned by your router; not routable on the open internet; looks like
10.x,172.16–31.x, or192.168.x - Public IP — works on the open internet; assigned by your ISP (or a VPN exit); globally routable; outside private and other special-purpose ranges
Private addresses are reserved so every home can reuse the same pools. Two neighbors can both use 192.168.1.1 for their router. That never collides on the public internet because those packets are not meant to leave the LAN as-is.
Private ranges you will actually see (RFC1918)
IPv4 private space is defined in RFC 1918. Memorize the three blocks:
10.0.0.0–10.255.255.255— common in larger LANs and some ISP gear172.16.0.0–172.31.255.255— mid-size networks, Docker defaults, some corp Wi‑Fi192.168.0.0–192.168.255.255— the classic home-router range (192.168.0.x/192.168.1.x)
Other special-purpose addresses have different jobs:
| Range | Type | Meaning |
|---|---|---|
127.0.0.0/8 |
Loopback | Communication within the same device; 127.0.0.1 is a familiar example |
169.254.0.0/16 |
Link-local | Communication on the local link; may appear when DHCP is unavailable |
100.64.0.0/10 |
Shared Address Space | Often used between customers and carrier-grade NAT equipment |
192.0.2.0/24, 198.51.100.0/24, 203.0.113.0/24 |
Documentation | Examples, not live public destinations |
These are not all RFC1918 private space. The IANA special-purpose registry lists the exact classifications and routing properties.
If Windows, macOS, or ipconfig / ip addr shows one of the RFC1918 ranges, that is your LAN address. It is not what a website in another country sees.
What your router is doing
Many home IPv4 setups use NAT (network address translation):
- Devices inside get private IPs from the router's DHCP.
- Outbound traffic leaves through the router.
- A website sees the address after the final translation, which may happen on the router or upstream at the ISP.
- Replies come back to that public address; the router maps them to the right private device.
So "what is my IP?" has two honest answers depending on which interface you ask. System settings answer the private question. A site like FindMyIP answers the public one.
Public IP: the one services log
Your public IP is the source address on packets that reach websites, games, mail servers, and APIs. That is the address analytics and security logs store, Geo-IP databases label with city / ISP (approximately), and blocklists often key off.
It may be:
- One public IPv4 for the whole household (typical home broadband)
- A carrier-grade shared address (see CGNAT below)
- A VPN exit address if a VPN is on
- IPv6 on networks that give you a global IPv6 — still internet-visible in the routing sense
For what that public label can imply (ISP, coarse location, tracking handle), see what your IP address reveals. This post stays on which class of address you are looking at.
CGNAT in one paragraph
Carrier-grade NAT (CGNAT) means the ISP puts many customers behind a shared public IPv4. Your router might still show a private-looking WAN address (often in 100.64.0.0/10, Shared Address Space), while FindMyIP shows the ISP's shared public IP.
Symptoms people notice: inbound port-forwarding fails; hosting a game from home needs IPv6, a tunnel product, or a different plan. Outbound browsing still works. If your WAN IP in the router UI is not a normal public address, another router or upstream NAT may be involved. Read carrier-grade NAT and shared public IPs and confirm the arrangement with the ISP.
How to tell which you have
1. Read the local address (private check)
On the device: system network settings, or ipconfig (Windows) / ifconfig or ip addr (macOS/Linux). If it sits in RFC1918 (or 100.64.0.0/10 on some WAN fields), it is not a globally unique public endpoint by itself.
2. Read the internet-facing address (public check)
Open What Is My IP. That page reports the address remote servers see right now — after Wi‑Fi, cellular, or VPN.
3. Inspect an address you found in a log
Paste it into IP Lookup. Private ranges will not geolocate like a normal customer address. Public ones usually show ISP/org and coarse location.
4. Compare before and after a VPN
The physical LAN address usually stays the same, although the VPN may add a virtual interface. A changed public IP checks only the request to FindMyIP, not every app or VPN setting.
Common mix-ups
- "My IP is 192.168.1.5 — how do hackers find me?" That number alone is not a global locator. Your public IP (and accounts or malware) are the usual exposure paths.
- Port forwarding "to 192.168…" from the internet — outsiders hit the public IP; the router must forward. CGNAT can prevent that path; a global address also needs appropriate firewall and service configuration.
- Phone on cellular vs home Wi‑Fi — different public IPs. Private IPs also differ per network.
- Two devices, same
192.168.1.10on different homes — normal. Private space is reused everywhere.
IPv4 vs IPv6 (only what you need here)
- IPv4 private = RFC1918 (above).
- IPv6 often gives devices global addresses; "private vs public" language is messier. Unique local addresses (
fc00::/7) are the LAN-ish cousins. If FindMyIP shows an IPv6, treat it as internet-visible unless you know it is local-only.
You may have IPv4, IPv6, or both in play at once. IPv4 versus IPv6 explains that distinction. Check each family separately when troubleshooting; a single FindMyIP result does not test both.
Privacy aside (not the main point)
Hiding a public IP from websites usually means changing the internet-facing address (for example with a VPN). That does not renumber your LAN's 192.168 devices. Private vs public is about scope; VPNs are about which public identity others see.
When the numbers disagree
Private IPs keep local traffic local. Public IPs are what the rest of the internet uses to talk to your connection. When numbers disagree across apps, check both layers: local settings for RFC1918, What Is My IP for the public view, and IP Lookup when you need to classify an address you found elsewhere.