If you've checked your IP address on our homepage, you may have noticed a badge saying "IPv4" or "IPv6." But what's the difference, and why should you care?
What Is IPv4?
IPv4 (Internet Protocol version 4) is the original addressing system for the internet, created in 1981. It uses 32-bit addresses written as four numbers separated by periods.
Example: 192.168.1.1
IPv4 supports approximately 4.3 billion unique addresses (2³²). That sounds like a lot, but with billions of internet-connected devices worldwide — smartphones, laptops, IoT devices, servers — we've essentially run out.
What Is IPv6?
IPv6 (Internet Protocol version 6) is the successor to IPv4, designed to solve the address shortage. It uses 128-bit addresses written in hexadecimal, separated by colons.
Example: 2001:0db8:85a3:0000:0000:8a2e:0370:7334
IPv6 supports approximately 340 undecillion (3.4 × 10³⁸) unique addresses. That's enough to assign a unique address to every atom on the surface of the Earth — and then some.
Key Differences
Here's a side-by-side comparison:
- Address Length: IPv4 uses 32 bits (4 bytes) vs IPv6's 128 bits (16 bytes)
- Address Format: IPv4 uses decimal (192.168.1.1) vs IPv6 uses hexadecimal (2001:db8::1)
- Total Addresses: IPv4: ~4.3 billion vs IPv6: ~340 undecillion
- Security: IPv4 has optional IPSec vs IPv6 has mandatory IPSec support
- NAT Required: IPv4 typically needs NAT vs IPv6 doesn't need NAT (each device gets a unique address)
- Header Size: IPv4 has a variable header (20-60 bytes) vs IPv6 has a fixed 40-byte header
- Speed: IPv6 can be slightly faster due to simpler header processing
Why Was IPv6 Created?
The primary reason is simple: we ran out of IPv4 addresses. The last blocks of IPv4 addresses were allocated to Regional Internet Registries in 2011. Since then, ISPs have used workarounds like NAT (Network Address Translation) and CGNAT to share IPv4 addresses among multiple users.
IPv6 provides virtually unlimited addresses, eliminating the need for these workarounds.
Do I Have IPv4 or IPv6?
Most people currently use both. Modern operating systems and ISPs support "dual-stack" — using IPv4 and IPv6 simultaneously. When you visit a website that supports IPv6, your device will use IPv6. Otherwise, it falls back to IPv4.
Check which version you're using right now at CheckWhatIsMyIP.com.
Privacy Implications
IPv6 has unique privacy considerations:
- Unique addresses: With IPv6, each device can have its own unique public address, making tracking easier
- Privacy extensions: Modern OSes generate temporary random IPv6 addresses to mitigate tracking
- VPN coverage: Some VPNs don't properly tunnel IPv6 traffic, creating leaks. Test with our VPN Leak Test
Summary
IPv6 is the future of the internet — it's faster, more secure, and has virtually unlimited addresses. While IPv4 isn't going away anytime soon (both protocols will coexist for years), the transition to IPv6 is steadily progressing worldwide.