IPv6 Subnet Calculator

Calculate IPv6 subnet parameters for any IPv6 CIDR prefix (e.g. `2001:db8::/64` or `fd00::/48`). Computes Network Prefix, Start/End Host Range, Subnet Mask, and total host capacity.

Why Use This Tool?

• IPv6 Infrastructure Planning: Plan global `/48`, `/56`, and `/64` IPv6 network allocations for data centers and cloud VPCs.
• Router Configuration: Verify start and end IPv6 address boundaries for BGP routing tables.
• Subnet Division: Subdivide a `/48` allocation into multiple `/64` subnets.

How to Use

1. Enter IPv6 Address and Prefix Length (e.g. `2001:db8:1234::/64`).
2. The tool computes network boundaries in real time.
3. View Expanded Prefix, Start Host IP, End Host IP, and Host Count.

Real Working Example

Input:

IPv6 Prefix: 2001:db8:1234:5678::/64

Output Result:

Network Prefix: 2001:0db8:1234:5678::/64
First Host IP: 2001:db8:1234:5678::1
Last Host IP: 2001:db8:1234:5678:ffff:ffff:ffff:ffff
Total /64 Hosts: 18,446,744,073,709,551,616 (18.4 Quintillion Hosts)

Important Technical Details & Standards

• 128-Bit Bitwise Subnet Math: Performs 128-bit BigInt calculations for hardware-accurate IPv6 range computation.
• Standard /64 Subnet Benchmark: Highlights standard /64 SLAAC interface subnet sizing.
• Local Memory Execution: Zero network overhead.

Related Networking & Security Tools

• IPv6 Expander & Compressor: Expand and compress IPv6.
• IPv6 ULA Generator: Generate private IPv6 addresses.
• IPv4 Subnet Calculator: Calculate IPv4 subnets.