Private vs Public IP Addresses: The Difference
Public IPs are globally unique and routable on the internet; private IPs are reused freely inside local networks and are not routable on the public internet. Private addresses reach the internet through NAT on your router.
The private (RFC 1918) ranges
| Range | Class | Size |
|---|---|---|
| 10.0.0.0 – 10.255.255.255 | A | ~16.7 million |
| 172.16.0.0 – 172.31.255.255 | B | ~1 million |
| 192.168.0.0 – 192.168.255.255 | C | ~65,000 |
If an address falls in these ranges, it's private. Everything else routable is public.
Why the split exists
IPv4 has only ~4.3 billion addresses — far too few for every device. Private ranges let millions of organisations reuse the same internal addresses, with NAT translating them to a small number of shared public IPs at the edge. This is the workaround that kept IPv4 alive; IPv6 solves it properly with a vast address space.
Frequently asked questions
What are the private IP address ranges?
10.0.0.0/8, 172.16.0.0/12 and 192.168.0.0/16 — reserved by RFC 1918 for use inside private networks.
Can a private IP access the internet?
Only through NAT, which translates the private address to a public one at the router. Private IPs are not routable on the public internet directly.
How can I tell if an IP is private or public?
If it falls within 10.x, 172.16–31.x or 192.168.x it's private; otherwise a routable address is public.
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