IPv4 vs IPv6 — What's the Difference?

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:

| Feature | IPv4 | IPv6 | | :--- | :--- | :--- | | Address Length | 32 bits (4 bytes) | 128 bits (16 bytes) | | Address Format | Decimal (192.168.1.1) | Hexadecimal (2001:db8::1) | | Total Addresses | ~4.3 billion | ~340 undecillion | | Security | Optional IPSec | Mandatory IPSec support | | NAT Required | Yes (typically) | No (each device gets unique address) | | Header Size | Variable (20-60 bytes) | Fixed (40 bytes) | | Speed | Standard | Slightly faster (simpler header) |

IPv6 Adoption Rates by Country (2025)

IPv6 adoption varies significantly by country. Here are the current adoption rates based on Google IPv6 statistics:

| Country | IPv6 Adoption Rate | | :--- | :--- | | France | 79% | | India | 72% | | Germany | 68% | | Japan | 55% | | United States | 51% | | United Kingdom | 43% | | Brazil | 38% | | Australia | 29% |

The United States currently has IPv6 adoption around 51%, meaning roughly half of all US internet traffic now uses IPv6. Germany and France lead Europe with over 65% adoption. Countries like Australia and Brazil still have significant IPv4 usage. You can check which protocol you are using right now with our free tool at CheckWhatIsMyIP.com.

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

Does Your VPN Protect Both IPv4 and IPv6?

This is one of the most important and overlooked questions for VPN users. Many VPN services only encrypt your IPv4 traffic by default. If your device is also making IPv6 connections — which it likely is on modern networks — those connections may bypass the VPN tunnel entirely, revealing your real IP address.

This is called an IPv6 leak. It is surprisingly common even with paid VPN services. Signs your VPN has an IPv6 leak: your VPN shows an IPv4 address but a different IPv6 address appears on leak test sites.

To check if your VPN is leaking your IPv6 address, use our free VPN Leak Test tool. It checks both your IPv4 and IPv6 addresses simultaneously and tells you immediately if there is a discrepancy.

How To Check Your IP Version Right Now

Want to know if you're using IPv4 or IPv6? Here's how to check in seconds:

Step 1: Visit checkwhatismyip.com

Step 2: Your IP version is shown instantly next to your IP address — either an IPv4 badge (green) or IPv6 badge (blue)

Step 3: If you are on IPv4, your address will look like four numbers separated by dots (e.g. 203.0.113.1)

Step 4: If you are on IPv6, your address will be a longer string of hexadecimal characters separated by colons

Step 5: If you are using a VPN, run the VPN Leak Test to confirm both your IPv4 and IPv6 traffic is protected

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.