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# IPv6 addresses – how many is that in numbers?

IPv6 is our Word of the Day today. The big difference between it andIPv4 is the increase in address space. IPv4 addresses are 32 bits; IPv6 addresses are 128 bits. That’s a lot more, for sure, but what does it look like in numbers? What could we compare it to in real-world terms?

How many IP addresses does IPv6 support? Well, without knowing the exact implementation details, we can get a rough estimate based on the fact that it uses 128 bits. So 2 to the power of 128 ends up being 340,282,366,920,938,000,000,000,000,000,000,000,000 unique IP addresses.

How do you say that, though?  340 trillion, 282 billion, 366 million, 920 thousand, 938 — followed by 24 zeroes.  There’s no short way to say it in numbers without resorting to math.

The very large IPv6 address space supports a total of 2128 (about 3.4×1038) addresses – or approximately 5×1028 (roughly 295) addresses for each of the roughly 6.5 billion (6.5×109) people alive today. In a different perspective, this is 252 addresses for every observable star in the known universe.

Steve Leibson takes a shot at putting it in real world terms. It’s big — grains of sand don’t even enter into it. No, he’s got to take it to the atomic level. Here’s his conclusion:

So 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. It isn’t remotely likely that we’ll run out of IPV6 addresses at any time in the future.

Rob Elamb takes a shot at expressing the number of possible IPv6 addresses in words:

First of all, he’s more precise with his numbers: 340,282,366,920,938,463,463,374,607,431,768,211,456

And he shows us how to say it:

340- undecillion
282- decillion
366- nonillion
920- octillion
938- septillion
463- sextillion
463- quintillion
607- trillion
431- billion
768- million
211- thousand
456

So, all words, that would look like:

Three hundred and forty undecillion, two hundred and eighty-two decillion, three hundred and sixty-six nonillion, nine hundred and twenty octillion, nine hundred and thirty-eight septillion, four hundred and sixty-three sextillion, four hundred and sixty-three quintillion, three hundred and seventy-four quadrillion, six hundred and seven trillion, four hundred and thirty-one billion, seven hundred and sixty-eight million, two hundred and eleven thousand, four hundred and fifty-six.

That’s a big number.

IPv4 allowed for four billion IP addresses, which must have seemed like plenty at the time. I guess the assumption was that not everyone on the planet would want an IP address and nobody’s coffee maker or toaster would need one. Just goes to show you, you never know.

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