IPv4 vs IPv6: What's the Difference?
By Daniel Last updated July 4, 2026
IPv4 and IPv6 are the two versions of the Internet Protocol in use today. IPv4 uses 32-bit addresses like 192.0.2.1 and ran out of new address space in 2011; IPv6 uses 128-bit addresses like 2001:db8::1 and is effectively inexhaustible. Most modern connections run both at once.
What is IPv4?
IPv4 (Internet Protocol version 4) was standardized in 1981 as RFC 791 and deployed across the early internet in 1983. It still carries a large share of traffic today. Its 32-bit addresses allow about 4.3 billion unique combinations, which seemed limitless in the 1980s but stopped being enough once phones, servers and smart devices came online by the billions. The end arrived on a specific date: on February 3, 2011, IANA, the registry that manages the global address pool, handed its last five blocks to the regional registries. Those registries then ran dry one by one, and RIPE NCC, which serves Europe and the Middle East, allocated its final addresses in November 2019. Since then, "new" IPv4 addresses mostly come from a resale market where blocks change hands for real money, and from NAT (Network Address Translation), which lets many devices share one public address. Both stretch the supply; neither creates more of it. If you want the basics first, start with what an IP address actually is.
What is IPv6?
IPv6 (Internet Protocol version 6) is the successor designed to end that scarcity permanently. The current specification is RFC 8200, published as a full internet standard in 2017 after nearly two decades of drafts. Its 128-bit addresses provide roughly 340 undecillion (3.4 × 10³⁸) possibilities, enough to give every device on earth its own public address many times over, with no NAT required just to get one. Instead, a firewall controls what can reach devices from outside. IPv6 also cleans up the packet format: the header is fixed at 40 bytes, drops the per-hop checksum, and moves rarely used options into extension headers, all of which makes routers' work simpler. One persistent myth needs correcting: IPsec support was originally mandatory in IPv6 and is now merely recommended (RFC 6434), and the same IPsec protocols run fine on IPv4. IPv6 does not encrypt your traffic by default.
IPv4 vs IPv6 at a glance
The core technical differences side by side:
| IPv4 | IPv6 | |
|---|---|---|
| Standardized | 1981 (RFC 791) | 2017 (RFC 8200, drafted 1998) |
| Address length | 32-bit | 128-bit |
| Format | Decimal, dotted | Hexadecimal, colon-separated |
| Example | 192.0.2.1 | 2001:db8:85a3::8a2e:370:7334 |
| Address space | ~4.3 billion | ~340 undecillion (3.4 × 10³⁸) |
| Configuration | Manual or DHCP | Autoconfiguration (SLAAC) or DHCPv6 |
| NAT | Commonly required | Not needed for addressing |
| IPsec support | Optional | Optional (originally required, now optional) |
| Header size | 20 bytes, variable | 40 bytes, fixed and simpler |
| Header checksum | Yes, recomputed at every hop | None, left to transport layer |
| Fragmentation | By sender and routers | By sender only |
| Broadcast | Yes | No, uses multicast instead |
Key differences
- Address space: IPv6's pool is so large it will not run out in any realistic timeframe; IPv4 depends on reuse, NAT and resale.
- No NAT: every IPv6 device can have its own public address, which simplifies peer-to-peer connections like gaming and video calls.
- Autoconfiguration: IPv6 devices can assign their own addresses (SLAAC) without a DHCP server, the service that hands out addresses on IPv4 networks.
- Simpler headers: IPv6's fixed 40-byte header, with no checksum to recompute at every hop, is cheaper for routers to process.
- No broadcast: IPv6 replaces broadcast with targeted multicast, reducing noise on large networks.
- Security: effectively a tie. IPsec is optional on both, and real-world encryption comes from TLS/HTTPS either way.
How much of the internet uses IPv6?
Adoption is further along than most people think. Google, which publishes a running measurement of how its users connect, currently sees around 45 percent of them arriving over IPv6 (Google IPv6 statistics). The share varies a lot by country and by network type: mobile carriers are the most aggressive adopters, with several large ones running IPv6-only internally, while many corporate and hosting networks lag years behind. Which protocol you connect with can even change where geolocation databases place you. See how accurate IP geolocation really is.
5.3% of the last 5422 visits to this site's home page arrived over IPv6. These are anonymous aggregate counters: we tally protocol versions only and store no IP addresses.
Dual stack, tunnels and NAT64
Dual stack is how most networks run today: your ISP assigns you both an IPv4 and an IPv6 address, and your device picks per connection. The "Happy Eyeballs" algorithm tries both in parallel and uses whichever answers faster, which is why the transition is invisible to you.
Tunneling was the early bridge: IPv6 packets wrapped inside IPv4 packets (mechanisms like 6in4 and 6rd) so IPv6 islands could talk across an IPv4-only internet. Tunnels still exist, but now that native IPv6 is widely available they are mostly a legacy or hobbyist tool.
NAT64/DNS64 solves the opposite problem: a network that is IPv6-only internally still needs to reach IPv4-only websites. A translator at the network edge synthesizes IPv6 addresses for IPv4 destinations and converts the traffic in flight. Large mobile carriers run this (usually with a companion mechanism called 464XLAT), so your phone may be IPv6-only without you ever noticing.
Is IPv6 faster than IPv4?
Not inherently. Your bandwidth depends on your plan and your line, not the protocol version, and independent measurements generally put IPv4 and IPv6 within a few percent of each other. IPv6 can win on latency in specific situations: there is no NAT translation step, and because providers built their IPv6 networks more recently, routes are sometimes shorter or less congested. It can also lose when a provider's IPv6 path is poorly peered. Treat protocol version as a wash for speed. It is not a reason to change anything.
Should you disable IPv6?
No. "Disable IPv6" survives as folk advice from the 2000s, when early implementations occasionally misbehaved, but today it creates problems rather than fixing them. On an IPv6-only or NAT64 network (common on mobile), disabling it means no connectivity at all. On dual-stack networks it forces everything through IPv4 and NAT, can add name-resolution delays while software waits for a protocol that never answers, and some operating system components (Windows in particular) are tested with IPv6 present and expected. If your actual concern is privacy, disabling a protocol does not hide you; masking your address does. See VPN vs proxy vs Tor for the honest trade-offs.
Check your own IP version
Want to see which versions your connection uses right now? Our What Is My IP Address tool shows your public IPv4 and IPv6 addresses side by side (along with your location and ISP) so you can tell instantly whether your network speaks IPv6. We never log or store your IP.