# IPv6 /29 Prefix – 34,359,738,368 /64 Subnets Explained

> An IPv6 /29 prefix spans 34,359,738,368 /64 subnets (633,825,300,114,114,700,748,351,602,688 addresses). Examples, roles and FAQs for planning IPv6 networks.

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# IPv6 /29 Prefix ReferenceIPv6

Eight operator blocks under one flag: a /29 spans 2^99 addresses — 633,825,300,114,114,700,748,351,602,688 of them — and divides into exactly eight whole /32s. Prefixes this short live above the level of a single ISP grant, marking the super-aggregates of the largest networks.

An IPv6 /29 prefix contains 633,825,300,114,114,700,748,351,602,688 addresses, which splits into 34,359,738,368 standard /64 subnets.

## /29 facts at a glance

- **Total addresses:** 633,825,300,114,114,700,748,351,602,688 (299)
- **/64 subnets inside:** 34,359,738,368
- **Host/interface bits:** 99
- **Example network:** 2001:db8::/29
- **First address:** 2001:db8::
- **Last address:** 2001:dbf:ffff:ffff:ffff:ffff:ffff:ffff
- **Typical role:** Large enterprise block (split from a /28-class allocation)

## A /29 in documentation space

Using `2001:db8::/32` (RFC 3849 documentation space) aligned to its own boundary, a /29 occupies:

| Block | First address | Last address |
| --- | --- | --- |
| 2001:db8::/29 | 2001:db8:: | 2001:dbf:ffff:ffff:ffff:ffff:ffff:ffff |

## How an IPv6 /29 prefix works

A /29 prefix pins the first 29 bits of a 128-bit address, leaving 99 bits free. That free portion holds 299 = 633,825,300,114,114,700,748,351,602,688 distinct addresses, and every such block begins at a multiple of that size. Because each subnet should be a /64, the 35 middle bits between the prefix and the /64 boundary give 34,359,738,368 subnets to hand out.

## Where /29 is used

- Announcing eight startup /32 allocations as one tidy BGP aggregate.
- Backbone operators whose addressing plans outgrow a single standard block.
- Special registry grants made to organizations with exceptional, documented scale.

The math is clean: a /29 equals two /30s, four /31s, or eight /32s. Registries part with blocks shorter than /32 sparingly, typically only after sustained, demonstrated utilization.

Cross-family caution: an IPv4 /29 carries 8 addresses, while its IPv6 namesake carries 2^99.

## Frequently asked questions

**How many /64s are in a /29?**

34,359,738,368. Thirty-five delegation bits separate the prefixes, and 2^35 lands at just under 34.4 billion standard subnets.

**How many /32s fit in a /29?**

Exactly eight. Three bits of difference means each step from /32 down to /29 doubles the count: 2, 4, 8.

**Is an IPv6 /29 the same thing as an IPv4 /29?**

Only the number matches. An IPv4 /29 holds 8 addresses; an IPv6 /29 holds 2^99 — an aggregate spanning eight entire ISP allocations.

**Can I request a /29 from an RIR?**

Possibly, but expect scrutiny: registries typically reserve blocks shorter than /32 for operators that document utilization far beyond an ordinary first allocation.

## Open this prefix in the calculator

[Open 2001:db8::/29 in the IPv6 calculator](https://itinsighthub.com/ipv6-subnet-calculator/?q=2001%3Adb8%3A%3A%2F29)

### Related IPv6 prefixes

[/32](https://itinsighthub.com/ipv6/32/)[/34](https://itinsighthub.com/ipv6/34/)[/36](https://itinsighthub.com/ipv6/36/)[/40](https://itinsighthub.com/ipv6/40/)[/42](https://itinsighthub.com/ipv6/42/)[/44](https://itinsighthub.com/ipv6/44/)[/47](https://itinsighthub.com/ipv6/47/)[/48](https://itinsighthub.com/ipv6/48/)[/52](https://itinsighthub.com/ipv6/52/)[/56](https://itinsighthub.com/ipv6/56/)[/60](https://itinsighthub.com/ipv6/60/)[/64](https://itinsighthub.com/ipv6/64/)[/127](https://itinsighthub.com/ipv6/127/)[/128](https://itinsighthub.com/ipv6/128/)

IPv6 /32 prefix →

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