fe80::/10 is the link-local prefix. Addresses in this range are valid only on a single link (network segment) and are used for neighbor discovery, router solicitation, and stateless autoconfiguration. They are never routed off the link.

What is the difference between /10 and /11?

A /10 is twice as large as /11. /10 has 2¹¹⁸ addresses; /11 has 2¹¹⁷. Each step down the prefix number doubles the address count.

How does /10 compare to /9?

A /9 is twice as large as /10. Moving from /10 to /9 adds one more fixed network bit, halving the host portion from 2¹¹⁸ to 2¹¹⁹ addresses.

How do I calculate an IPv6 /10 subnet?

Enter an IPv6 address and select prefix /10 in the calculator above — or paste full CIDR notation like 2001::/10. The tool instantly returns the network address, address range, prefix mask, reverse DNS, and total count of 2¹¹⁸ addresses.

IPv6 /10 Subnet Calculator

Results update as you type

A /10 such as fe80::/10 defines the link-local range. Every IPv6 interface automatically configures a link-local address used for neighbor discovery and on-link communication. As an allocation size, a /10 holds 2¹¹⁸ addresses — astronomically large and never assigned to a single organization.

Prefix length

/128

/10 = 2¹¹⁸ addresses (≈ 3.32 × 10³⁵)

Results for 2000::/10

Global UnicastGlobal 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 /10

Total addresses≈ 3.32 × 10³⁵ addresses

Address typeGlobally routable scope

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

Neighboring /10 subnets

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

Hextet breakdown

20010000000000000000000000000000

NetworkSplit groupHost

Quick facts for IPv6 /10

Prefix mask: ffc0::
Total addresses: 2¹¹⁸
Approx. count: 3.32 × 10³⁵
/64 subnets: 2⁵⁴

IPv6 /10 reference guideBit split, overview, key facts, sizing tables, design notes, standards, and FAQ

Network / host bit split

mixhosthosthosthosthosthosthost

Network bits (10)Split hextetHost bits (118)

Network bits: 10
Host bits: 118
Prefix mask: ffc0::
Total addresses: 2¹¹⁸
Approx. count: 3.32 × 10³⁵
/64 subnets: 2⁵⁴
Addresses formula: 2^118
/64 relationship: 2⁵⁴ × /64 subnets

Overview

Common use cases

Link-local addressing (fe80::/10)
Very large reserved-range documentation

Key facts

A /10 fixes 10 network bits and leaves 118 host bits — 2¹¹⁸ total addresses.
In network design terms, /10 is typically a IANA reserved / special-purpose block.
You can subnet a /10 into about 2⁵⁴ /64 LANs.
At site scale, /10 equals about 2³⁸ /48 allocations.
At ISP scale, /10 contains about 2²² /32 blocks.

Design guidance

A /10 is not a size you assign to a LAN or site. Treat it as documentation of how the IPv6 address space is carved at the top of the hierarchy. When studying for certifications, focus on which well-known ranges (2000::/3, fe80::/10, fc00::/7, ff00::/8) live inside or beside this block.

Practical example

Addresses like 2001::/10 fall in reserved or special-purpose space. They illustrate how a /10 boundary groups addresses for routing policy, not how you would number a home LAN.

Related RFCs and standards

RFC 4291IPv6 Addressing Architecture
RFC 3849IPv6 Documentation Address Prefix (2001:db8::/32)
RFC 4291Link-Local Addresses (fe80::/10)

Prefix sizing reference

Divide /10 into…

Prefix	Subnets	Addresses each
/11	2	2¹¹⁷
/12	4	2¹¹⁶
/14	16	2¹¹⁴
/18	256	2¹¹⁰

/10 fits inside…

Supernet	Addresses	/10s inside
/9	2¹¹⁹	2
/8	2¹²⁰	4
/6	2¹²²	16
/2	2¹²⁶	256

Notable /10 networks

fe80::/10Link-local unicast
2001:db8::/32Documentation prefix (RFC 3849)

Frequently asked questions

Common questions about IPv6 /10 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