The IPv6 address space contains exactly 340,282,366,920,938,463,463,374,607,431,768,211,456 unique addresses. This staggering number, expressed mathematically as 2^128, is commonly referred to as 340 undecillion or approximately 3.4 × 10^38 addresses.
To put this in perspective: IPv6 provides an address space so vast that it fundamentally redefines what's possible with internet connectivity. Unlike its predecessor IPv4, which ran out of addresses years ago, IPv6 ensures we'll never face address exhaustion again—at least not for millions of years.
IPv6 uses a 128-bit addressing scheme, compared to IPv4's 32-bit system. This difference might seem modest on paper, but it creates an exponential explosion in available addresses.
The calculation is straightforward:
This means IPv6 has approximately 79 octillion times more addresses than IPv4. To visualize this ratio: if IPv4's address space were the size of a golf ball, IPv6's address space would be larger than the Sun.
| Protocol | Bits | Total Addresses | Written Out |
|---|---|---|---|
| IPv4 | 32 | ~4.3 billion | 4,294,967,296 |
| IPv6 | 128 | ~340 undecillion | 340,282,366,920,938,463,463,374,607,431,768,211,456 |
| Ratio | 4x larger | 79 octillion times larger | IPv6 ÷ IPv4 ≈ 7.9 × 10^28 |
For context, IPv4 allocated roughly one address per person on Earth (with the global population around 8 billion). By the time IPv4 exhaustion occurred in 2011, we simply didn't have enough addresses to accommodate the explosive growth of internet-connected devices.
With a global population of approximately 8 billion people, IPv6 provides:
~42,535,295,865,117,307,932,921,825,928,971,026,432 addresses per person
That's approximately 42 undecillion addresses for every human being alive today—or roughly 5 × 10^28 addresses per person.
To break this down further:
The scale of IPv6 is difficult for the human mind to grasp. Here are some comparisons that help illustrate just how many addresses we're talking about:
If you collected every grain of sand from every beach on Earth, you'd have far fewer grains than IPv6 addresses. In fact, IPv6 provides more than 10 million trillion times the total number of grains of sand on all the world's beaches combined.
One calculation suggests there are approximately 664 billion IPv6 addresses for every grain of sand in Earth's crust (assuming a depth of one mile).
The often-quoted comparison is accurate: "We could assign an IPv6 address to every atom on the surface of the Earth, and still have enough addresses left to do another 100+ Earths."
The mathematics confirms this:
If we started assigning IPv6 addresses at a rate of one billion addresses per second, it would take approximately 10 trillion years to exhaust the address space—roughly 750 times the current age of the universe.
Some estimates suggest we won't need to worry about IPv6 exhaustion until around the year 9,000,000 AD, assuming current growth trends.
Given these mind-boggling numbers, a reasonable question emerges: why does IPv6 need such a massive address space? Isn't this overkill?
The explosive growth of internet-connected devices is the primary driver:
By some estimates, the number of internet-connected devices will exceed 125 billion by 2030. IPv4's 4.3 billion addresses simply cannot accommodate this growth.
IPv6 eliminates the need for Network Address Translation (NAT), which was a workaround developed to extend IPv4's lifespan. With IPv6:
IPv6's large address space enables more efficient routing through hierarchical allocation:
The designers of IPv6 intentionally created an address space large enough to last indefinitely:
While the theoretical address space is enormous, practical IPv6 adoption varies by region and Internet Service Provider. Not all networks have fully transitioned to IPv6, and many users operate in "dual-stack" environments where both IPv4 and IPv6 coexist.
Understanding your own network's IPv6 readiness is important for ensuring optimal connectivity and future compatibility. Tools like test-ipv6.run can help you determine whether your connection supports IPv6, evaluate your network's dual-stack capabilities, and identify any connectivity issues that might affect your access to modern internet services.
IPv6's 340 undecillion addresses represent one of the most dramatic expansions in technological capacity in computing history. This isn't just a incremental upgrade—it's a fundamental reimagining of how internet addressing works.
The transition from IPv4 to IPv6 can be compared to moving from a world where street addresses were limited to a single small city (4.3 billion addresses) to a system that can uniquely address not just every building on Earth, but every atom on multiple Earths simultaneously.
While we may never use all 340 undecillion addresses, this abundance brings tremendous benefits:
The question isn't whether IPv6 has "too many" addresses—it's whether we've finally learned from IPv4's limitations and built a system that will truly never run out.
Key Takeaways: