What is the difference between a public IP and a private IP?
A public IP is the one address your internet provider assigns to your home or office connection, visible to the whole internet, while a private IP only works inside your own router and network. ipnow.kr shows your public IP the moment you open it.
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What is a public IP address?
A public IP is assigned by your internet service provider to your home or office line, and it is unique across the entire internet. Servers use it to know where to send their response.
One router at home receives a single public IP from the provider, and every device behind it, a PC, a phone, a TV, reaches the internet through that same address. The address shown on What is my IP address is this public IP.
What is a private IP address?
A private IP only works inside your own network, shared by devices connected to the same router or Wi-Fi. The router hands one out to each device automatically from a reserved range.
Addresses starting with 192.168. are the most common at home, while offices often use 10.0.0.5 or 172.16.0.20 style ranges. See find your IP on Windows and find your IP on Mac to check the private IP of any device.
- 192.168.0.0/16 - most common on home routers
- 10.0.0.0/8 - common on office and large networks
- 172.16.0.0/12 - used by some routers and businesses
Why is a private IP invisible from outside the network?
Your router uses NAT (Network Address Translation) to translate every private IP inside your home into the one public IP your provider assigned, before sending traffic out. That is why an outside website only ever sees one public IP, no matter how many devices you have.
Some providers translate the address again inside their own equipment, so even the address a router shows as its WAN IP is not the real public IP; this is called CGNAT. See what is CGNAT for details.
Is 127.0.0.1 a private IP too?
No. Unlike a private IP, 127.0.0.1 is a loopback address that always points back to the device you are using right now. It never leaves the device, so no other device can reach it.
Read more about loopback addresses in localhost and 127.0.0.1.
| Item | Value | Source |
|---|---|---|
| Private IPv4 ranges | 10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16 | RFC 1918 · 1996-02 |
Frequently asked questions
Where can I check the public IP of my router?
Open ipnow.kr and your public IP appears immediately on the first screen. You can also find it under the WAN status in the admin page of your router.
Can someone reach my computer from outside using only my private IP?
No. A private IP only works inside your own router, so reaching it from outside requires port forwarding or your public IP.
Why does every device at home get a different private IP?
Your router uses a feature called DHCP to hand out a different private IP to each connected device automatically. The public IP is shared by the whole router, but private IPs are assigned per device.
Can I choose my own private IP range?
Most home routers default to the 192.168.0.0/16 range, and you can change it in the router settings, but keeping the default is usually the safer choice unless you have a specific reason to change it.