Private vs Public IP Addresses Explained
Every device has IP addresses, but not all of them are visible to the open internet. Your router and ISP use a public IP to communicate on the web, while devices inside your home or office typically use private IPs that are not routable on the public internet. This guide explains how the two types differ, shows common IPv4/IPv6 ranges, how NAT connects them, and how to quickly check what the world actually sees when you go online.
What is a public IP?
A public IP is an address that’s reachable over the public internet. It identifies your connection (or VPN exit) to websites and services. Public IPs are globally unique and are allocated to networks by registries and ISPs.
What is a private IP?
A private IP is used inside local networks (LANs). These addresses are not routed on the internet and can be reused by many networks worldwide. Routers translate private addresses to a single public IP via Network Address Translation (NAT).
Common IPv4 private ranges
10.0.0.0 – 10.255.255.255(10/8)172.16.0.0 – 172.31.255.255(172.16/12)192.168.0.0 – 192.168.255.255(192.168/16)
These are defined for private use and appear on home routers, office LANs and hotspots.
IPv6 equivalents (at a glance)
- ULA — Unique Local Address:
fc00::/7(commonlyfdxx:prefixes) — similar to private space, not routable globally. - Link‑local:
fe80::/10— auto‑configured for communication on the local link only. - Global unicast: starts outside the above — routable on the public internet (your “public” IPv6).
Private vs Public: key differences
| Property | Private IP | Public IP |
|---|---|---|
| Scope | Local network (LAN) | Global internet |
| Uniqueness | Not globally unique (reused) | Globally unique |
| Routability | Not routed on the internet | Routed across the internet |
| Typical owner | End users / internal networks | ISPs / data centers / VPN exits |
| Security view | Hidden behind NAT by default | Exposed entry point to your network |
How NAT connects private and public IPs
NAT lets many devices share one public IP. Outbound traffic is mapped to the router’s public IP with unique port numbers. Replies come back to the router, which forwards them to the correct private device. This is why sites usually see a single public IP even though multiple devices are online behind the same router.
How to check which one you expose
- Open What is My IP — this shows the public IP the internet sees (or your VPN’s exit IP).
- On your device, find your private IP:
- Windows:
ipconfig→ IPv4 Address - macOS/Linux:
ifconfig/ip addr→inet/inet6 - Router admin → LAN / DHCP list
- Windows:
- If you use VPN, your public IP should change to the VPN server. Verify no leaks with WebRTC and DNS Lookup.
Privacy & security tips
- Prefer a VPN on public Wi‑Fi to avoid exposing your real public IP.
- Keep router firmware updated; disable unnecessary port forwarding and UPnP.
- Use strong admin passwords and enable the firewall on router and OS.
- Separate IoT devices on a guest or VLAN network.
Check now: See your public IP on What is My IP and confirm no exposure via WebRTC and DNS.