IPv4 vs IPv6: What's the Difference and Why It Matters

The internet is in the middle of its biggest upgrade ever: the slow migration from IPv4 to IPv6. Most people never notice it happening — but it affects how your connection works, how you're identified online, and occasionally why something breaks.

The core problem: IPv4 ran out

IPv4 uses 32-bit addresses, which allows about 4.3 billion unique addresses. That seemed infinite in 1981. Today, with phones, laptops, TVs, cars and lightbulbs all online, it's nowhere near enough. The last free IPv4 blocks were handed out years ago; addresses are now bought, sold and recycled.

IPv6 uses 128-bit addresses — roughly 340 undecillion (3.4×10³⁸) of them. Every device on Earth could have trillions of its own addresses without running out.

Side-by-side comparison

Is IPv6 faster?

Slightly, in many cases. IPv6 traffic often takes a more direct route because it avoids NAT and carrier-grade NAT layers. Real-world differences are small — usually a few milliseconds — but gamers and video callers sometimes notice smoother connections on IPv6-enabled networks.

Privacy differences

There's a real distinction here. With IPv4, your whole household shares one public address. With IPv6, each device can have its own globally unique address — which is better for connectivity but potentially worse for privacy. Modern devices counter this with privacy extensions that rotate the device part of the address regularly.

Which one am I using?

Check the homepage — the "IP Version" field tells you instantly. Many connections have both (called dual-stack): your device prefers IPv6 when a site supports it and falls back to IPv4 when it doesn't.

Frequently asked questions