IPv4 vs IPv6: What's the Difference?
Updated May 31, 2026
The internet currently runs on two versions of the Internet Protocol: IPv4 and IPv6. Both do the same fundamental job — routing data between devices — but they differ enormously in scale.
The core difference: address space
IPv4 uses 32-bit addresses, which allows for about 4.3 billion unique addresses. That sounded limitless in the 1980s, but with billions of phones, computers and smart devices online, the world ran out.
IPv6 uses 128-bit addresses, providing roughly 340 undecillion addresses (that's 340 followed by 36 zeros) — effectively unlimited.
| | IPv4 | IPv6 |
|---|---|---|
| Address length | 32-bit | 128-bit |
| Example | 192.0.2.1 | 2001:db8::1 |
| Total addresses | ~4.3 billion | ~340 undecillion |
| Notation | Decimal, dot-separated | Hexadecimal, colon-separated |
Why IPv6 was created
As IPv4 addresses ran out, providers leaned on workarounds like NAT to share one public address across many devices. NAT works, but it adds complexity and can break certain peer-to-peer applications. IPv6 removes the scarcity entirely, so every device can have its own globally unique address again.
Other IPv6 advantages
- Simpler routing — more efficient packet headers reduce the work routers do.
- Built-in autoconfiguration — devices can self-assign addresses without DHCP.
- No NAT required — restoring true end-to-end connectivity.
Why both still exist
The two protocols aren't directly compatible, so the internet is in a long transition. Most networks run dual-stack, supporting IPv4 and IPv6 at the same time. That's why our home page may show you an IPv4 address, an IPv6 address, or both — it depends on what your ISP has enabled.
If you only see an IPv4 address, your network simply hasn't turned on IPv6 yet. This is still very common and nothing to worry about.
Key takeaways
- IPv4 is older and nearly exhausted; IPv6 offers a virtually unlimited supply.
- IPv6 brings simpler routing and removes the need for NAT.
- Most of the internet runs both protocols side by side during the transition.