# IPv6 /36 Prefix – 268,435,456 /64 Subnets Explained

> An IPv6 /36 prefix spans 268,435,456 /64 subnets (4,951,760,157,141,521,099,596,496,896 addresses). Examples, roles and FAQs for planning IPv6 networks.

- Page URL: https://itinsighthub.com/ipv6/36/
- Markdown variant of this page: append `?format=md` to any URL on this site or send `Accept: text/markdown`.
- Full site index for AI assistants: https://itinsighthub.com/llms.txt
- Full site export: https://itinsighthub.com/llms-full.txt

# IPv6 /36 Prefix ReferenceIPv6

The quiet middleweight of IPv6 planning: a /36 packs 268,435,456 /64 subnets into a block that reads cleanly in hexadecimal and splits on every convenient boundary. Too small for an ISP's opening hand yet far bigger than one building — it belongs to large campuses and platform builders.

An IPv6 /36 prefix contains 4,951,760,157,141,521,099,596,496,896 addresses, which splits into 268,435,456 standard /64 subnets.

## /36 facts at a glance

- **Total addresses:** 4,951,760,157,141,521,099,596,496,896 (292)
- **/64 subnets inside:** 268,435,456
- **Host/interface bits:** 92
- **Example network:** 2001:db8::/36
- **First address:** 2001:db8::
- **Last address:** 2001:db8:fff:ffff:ffff:ffff:ffff:ffff
- **Typical role:** Mid-size ISP allocation

## A /36 in documentation space

Using `2001:db8::/32` (RFC 3849 documentation space) aligned to its own boundary, a /36 occupies:

| Block | First address | Last address |
| --- | --- | --- |
| 2001:db8::/36 | 2001:db8:: | 2001:db8:fff:ffff:ffff:ffff:ffff:ffff |

## How an IPv6 /36 prefix works

A /36 prefix pins the first 36 bits of a 128-bit address, leaving 92 bits free. That free portion holds 292 = 4,951,760,157,141,521,099,596,496,896 distinct addresses, and every such block begins at a multiple of that size. Because each subnet should be a /64, the 28 middle bits between the prefix and the /64 boundary give 268,435,456 subnets to hand out.

## Where /36 is used

- Large enterprise campuses that want room to route hundreds of segments.
- Hosting and cloud platforms subdividing the block into tidy /40s or /44s.
- Mid-tier operators growing toward a fuller /32 over time.

Every split is clean: a /36 yields sixteen /40s, 256 /44s, or 4,096 /48s — all nibble-friendly sizes for reverse DNS.

Position matters in the ladder: sixteen /36s tile a /32, and sixteen /40s tile a /36 — a neat geometric progression for planners.

## Frequently asked questions

**How many /40s are in a /36?**

Sixteen. Four bits of difference, so the /36 divides evenly into 16 blocks of /40.

**How many addresses does a /36 contain?**

4,951,760,157,141,521,099,596,496,896 — which is 2^92, all inside a prefix that still fits on one clean BGP announcement.

**Is a /36 bigger than a /48?**

Considerably: 4,096 times bigger, since twelve bits separate them. A /36 holds 4,096 classic site allocations.

**Would an ISP hand me a /36?**

Unusual as a formal allocation, but perfectly normal as an internally carved slice of a larger grant or a special arrangement for a heavyweight customer.

## Open this prefix in the calculator

[Open 2001:db8::/36 in the IPv6 calculator](https://itinsighthub.com/ipv6-subnet-calculator/?q=2001%3Adb8%3A%3A%2F36)

### Related IPv6 prefixes

[/29](https://itinsighthub.com/ipv6/29/)[/32](https://itinsighthub.com/ipv6/32/)[/34](https://itinsighthub.com/ipv6/34/)[/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 /34 prefix
IPv6 /40 prefix →

---

© 2026 ITInsightHub · [About](https://itinsighthub.com/about/) · [Contact](https://itinsighthub.com/contact/) · [Privacy](https://itinsighthub.com/privacy/)