How many addresses are in an IPv6 /26?

An IPv6 /26 contains 2¹⁰² addresses. The prefix fixes the first 26 bits; the remaining 102 bits identify individual addresses in the block.

How many /64 subnets fit in a /26?

A /26 can be divided into 2³⁸ standard /64 LAN subnets. Each /64 holds 2⁶⁴ addresses, so the combined block is effectively inexhaustible for normal use.

How many /48 site allocations are in a /26?

A /26 contains 2²² /48 site allocations. A /48 is the classic size assigned to a business site or campus.

What is the difference between /26 and /27?

A /26 is twice as large as /27. /26 has 2¹⁰² addresses; /27 has 2¹⁰¹. Each step down the prefix number doubles the address count.

How does /26 compare to /25?

A /25 is twice as large as /26. Moving from /26 to /25 adds one more fixed network bit, halving the host portion from 2¹⁰² to 2¹⁰³ addresses.

Is IPv6 /26 the same as IPv4 /26?

No. IPv4 /26 has at most a few thousand hosts. IPv6 /26 still contains 2¹⁰² addresses — an aggregation size in the IPv6 hierarchy, not a LAN subnet. IPv6 LANs are almost always /64.

IPv6 /26 Subnet Calculator

Results update as you type

A /26 block fixes the first 26 bits of the address, leaving 102 host bits and 2¹⁰² total addresses. It subdivides into about 2³⁸ /64 LAN subnets. That is also about 2²² /48 site allocations. At the ISP tier, a /26 holds 2⁶ /32 ISP blocks. Prefixes in this range appear in BGP tables and RIR allocation policies as aggregation blocks above the standard ISP /32.

Prefix length

/128

/26 = 2¹⁰² addresses (≈ 5.07 × 10³⁰)

Results for 2001:d80::/26

Documentation (RFC 3849)Global scope

Network / prefixThe first address — identifies the subnet itself

First addressSubnet-router anycast; first address in the block

Last addressThe highest address in this block

Prefix maskEquivalent to /26

Total addresses≈ 5.07 × 10³⁰ addresses

Address typeGlobally routable scope

More detailsNeighboring subnets, expanded address, reverse DNS, and hextet breakdown

Neighboring /26 subnets

Expanded address
Compressed address
Network (expanded)
Last address (expanded)
Prefix mask
Total addresses (exact)
Reverse DNS (PTR)
Host bits / network bits

Hextet breakdown

20010db8000000000000000000000000

NetworkSplit groupHost

Quick facts for IPv6 /26

Prefix mask: ffff:ffc0::
Total addresses: 2¹⁰²
Approx. count: 5.07 × 10³⁰
/64 subnets: 2³⁸

IPv6 /26 reference guideBit split, overview, key facts, sizing tables, design notes, standards, and FAQ

Network / host bit split

netmixhosthosthosthosthosthost

Network bits (26)Split hextetHost bits (102)

Network bits: 26
Host bits: 102
Prefix mask: ffff:ffc0::
Total addresses: 2¹⁰²
Approx. count: 5.07 × 10³⁰
/64 subnets: 2³⁸
Addresses formula: 2^102
/64 relationship: 2³⁸ × /64 subnets

Overview

Common use cases

Aggregating ISP /32 allocations in routing tables
Regional provider address planning
Large-scale subnetting study and documentation

Key facts

A /26 fixes 26 network bits and leaves 102 host bits — 2¹⁰² total addresses.
In network design terms, /26 is typically a large provider aggregation block.
You can subnet a /26 into about 2³⁸ /64 LANs.
At site scale, /26 equals about 2²² /48 allocations.
At ISP scale, /26 contains 2⁶ /32 blocks.

Design guidance

A /26 belongs in BGP aggregation and RIR allocation planning — not on a VLAN interface. If you are subnetting for a real deployment, work downward: carve /48 or /56 site blocks first, then assign one /64 per LAN. Announcing a single aggregated /26 (or larger) upstream keeps global routing tables manageable.

Practical example

An ISP holding 2001:db8::/26 might announce the entire /26 to upstream providers as one BGP route, then delegate /48 blocks such as 2001:db8:0001::/48 and 2001:db8:0002::/48 to business customers. Each customer subnets their /48 into /64 LANs.

Related RFCs and standards

RFC 4291IPv6 Addressing Architecture
RFC 3849IPv6 Documentation Address Prefix (2001:db8::/32)

Prefix sizing reference

Divide /26 into…

Prefix	Subnets	Addresses each
/27	2	2¹⁰¹
/28	4	2¹⁰⁰
/30	16	2⁹⁸
/34	256	2⁹⁴

/26 fits inside…

Supernet	Addresses	/26s inside
/25	2¹⁰³	2
/24	2¹⁰⁴	4
/22	2¹⁰⁶	16
/18	2¹¹⁰	256

Notable /26 networks

2001:db8::/32Documentation prefix (RFC 3849)

Frequently asked questions

Common questions about IPv6 /26 blocks, prefix sizes, and use cases.

Common IPv6 prefix sizes

/3 /12 /16 /20 /24 /28 /32 /36 /40 /44 /48 /52 /56 /60 /64 /80 /96 /112 /120 /124 /126 /127 /128