IPv6 Subnet & Prefix Calculator

Enter an IPv6 prefix like 2001:db8::/48 to see its range, size and how it splits into /56 or /64 networks.

IPv4 & IPv6 · your network layout never leaves the browser

/481.20 × 10^24 addr

2001:db8::/48

Documentation

Network2001:db8::

Prefix/48

Host mask::ffff:ffff:ffff:ffff:ffff

First usable2001:db8::1

Last usable2001:db8:0:ffff:ffff:ffff:ffff:ffff

Total addresses1.20 × 10^24

Usable hosts1.20 × 10^24

Details

Use in examples; never routed.

Reverse DNS zone0.0.0.0.8.b.d.0.1.0.0.2.ip6.arpa

Expanded2001:0db8:0000:0000:0000:0000:0000:0000

Integer42540766411282592856903984951653826560

00100000000000010000110110111000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000

Mask

11111111111111111111111111111111111111111111111100000000000000000000000000000000000000000000000000000000000000000000000000000000

48 network bits · 80 host bits

Split into subnets

#	Subnet	First host	Last host
1	2001:db8::/50	2001:db8::1	2001:db8:0:3fff:ffff:ffff:ffff:ffff
2	2001:db8:0:4000::/50	2001:db8:0:4000::1	2001:db8:0:7fff:ffff:ffff:ffff:ffff
3	2001:db8:0:8000::/50	2001:db8:0:8000::1	2001:db8:0:bfff:ffff:ffff:ffff:ffff
4	2001:db8:0:c000::/50	2001:db8:0:c000::1	2001:db8:0:ffff:ffff:ffff:ffff:ffff

Loading Tool...

Help shape IPv6 Subnet & Prefix Calculator

The bug you just noticed will fade in 3 minutes. The feature idea will vanish after your next tab switch. Crazy peps don't suffer silently.

0/1000

Discord Contribute

Frequently Asked Questions

65,536. Each extra prefix bit halves the size, and a /48 has 16 bits before /64.

SLAAC auto-configuration expects 64-bit interface IDs, so almost every IPv6 LAN is a /64.

Link-local addresses, configured automatically on every interface and never routed.

Reverse the hex nibbles of the prefix and append ip6.arpa — the calculator shows it for you.

Subnet

First host

Last host

2001:db8::/50

2001:db8::1

2001:db8:0:3fff:ffff:ffff:ffff:ffff

2001:db8:0:4000::/50

2001:db8:0:4000::1

2001:db8:0:7fff:ffff:ffff:ffff:ffff

2001:db8:0:8000::/50

2001:db8:0:8000::1

2001:db8:0:bfff:ffff:ffff:ffff:ffff

2001:db8:0:c000::/50

2001:db8:0:c000::1

2001:db8:0:ffff:ffff:ffff:ffff:ffff

Continue with a nearby utility

CIDR & Subnet Calculator for IPv4 and IPv6

IP Subnet Calculator

VLSM Subnet Planner & Calculator

Nginx Config Generator & Reverse Proxy Builder

Frequently Asked Questions