How many IPv4 addresses are there?

IP Addresses
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4,294,967,296. That is the total number of IPv4 addresses that exist. Not one more. The figure is fixed by the very structure of the protocol, defined in the early 1980s at a time when nobody imagined billions of devices would one day need an internet connection. Today that pool is virtually exhausted, and the consequences reach everyone from hosting providers to everyday users.

Where does the 4.3 billion figure come from?

An IPv4 address is encoded on 32 bits. Each bit can be 0 or 1, which gives 2 to the power of 32 possible combinations, or exactly 4,294,967,296 addresses. It is a hard mathematical ceiling: you cannot "create" new IPv4 addresses, just as you cannot add phone numbers without changing the numbering format.

To put that in perspective: if every human on Earth needed just one IPv4 address, we would already be short by more than 3.7 billion. In reality, a single connected household often uses several addresses (router, phones, laptops, smart devices), and that is before counting the servers, data centres and network equipment run by businesses.

Not all addresses are usable

Of the 4.3 billion theoretical addresses, a significant portion cannot be assigned to devices on the public internet. Several ranges are reserved for specific purposes:

  • 10.0.0.0/8 (16.7 million addresses): private networking, used in corporate LANs and home routers
  • 172.16.0.0/12 (roughly 1 million): private networking
  • 192.168.0.0/16 (65,536 addresses): private networking, the range you see at home (192.168.1.x)
  • 127.0.0.0/8 (16.7 million): loopback, reserved for the local machine (the well-known 127.0.0.1 or "localhost")
  • 224.0.0.0 through 255.255.255.255 (roughly 268 million): multicast and reserved

All told, around 600 million addresses are reserved and cannot be handed out on the internet. That leaves roughly 3.7 billion usable public addresses in theory.

Who owns these addresses?

Public IPv4 addresses are managed by IANA (Internet Assigned Numbers Authority), which distributes them to five Regional Internet Registries covering different parts of the globe: RIPE NCC for Europe, ARIN for North America, APNIC for Asia-Pacific, LACNIC for Latin America, and AFRINIC for Africa.

These registries then allocate blocks to ISPs and large organisations. The distribution is very uneven. The United States, as the birthplace of the internet, holds a disproportionate share. MIT alone owns an entire /8 block, meaning 16.7 million addresses. Apple, Ford, and the US Department of Defense each hold their own large blocks. Some of these organisations have started selling unused portions, since a single IPv4 address trades for between $30 and $60 on the secondary market.

When did IPv4 addresses run out?

IANA distributed its last blocks to the regional registries in February 2011. Since then, each registry has gradually depleted its own pool:

  • APNIC (Asia-Pacific): April 2011
  • RIPE NCC (Europe): September 2012, then full exhaustion in November 2019
  • LACNIC (Latin America): June 2014
  • ARIN (North America): September 2015
  • AFRINIC (Africa): January 2020

Today, the only ways to obtain public IPv4 addresses are to buy them on the secondary market, reclaim returned blocks, or join a waiting list at the regional registry. For a new player entering the hosting or telecom market, it is a genuine financial barrier.

How the internet keeps growing despite the shortage

If addresses ran out years ago, how does the internet keep expanding? Several mechanisms have bought time:

NAT (Network Address Translation) lets hundreds of devices share a single public IPv4 address. Your home router does this: all your devices get a private IP (192.168.x.x), and your ISP assigns you one public IP. CGNAT (Carrier-Grade NAT) takes it further by making multiple households share one public IP, which more and more ISPs do, especially on mobile plans.

Recycling: organisations that held enormous underused blocks (like the US Department of Defense or certain universities) have sold portions back. In 2024, the average price of an IPv4 address on the secondary market sat between $35 and $50.

And of course IPv6, which is the real long-term solution. IPv6 uses 128-bit addresses, yielding 340 sextillion possible addresses (3.4 × 10³⁸). For scale, that is enough to give several billion addresses to every grain of sand on Earth. The catch: the transition is slow, and as of 2026, roughly 45% of global internet traffic runs over IPv6 according to Google's measurements.

What this means for you

As a user, the IPv4 shortage affects you in several ways, even if it is not always obvious. If your ISP uses CGNAT, you share your public IP with other subscribers, which can cause problems with hosting a home server, online gaming (some titles need a dedicated IP for open NAT), or services like remotely accessible security cameras.

To check whether your ISP gives you a dedicated public IPv4 address or a shared one via CGNAT, visit ipme.co and compare the address shown with the one in your router settings. If they differ, you are likely behind CGNAT.

IPv4 addresses are a finite resource that nobody can expand. Moving to IPv6 is no longer an interesting technical option but a necessity. If you manage a website, a server, or network infrastructure, check that your hosting provider supports IPv6 and enable it. For home use, most recent routers handle it automatically if your ISP offers it.