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IPv6 Subnet & Address Calculator

Normalize IPv6 text and calculate prefix boundaries and exact address counts. Work locally without uploading network information.

Runs entirely on your deviceNo uploads, accounts, cookies, or personal tracking.

Calculate IPv6 prefix

Local processing · no input storage

Network tools
Supports compressed and IPv4-mapped addresses. Omit the prefix for /128; zone IDs and brackets are not accepted.

Shows full prefix ranges, not an assignable-host policy. Address counts use exact 128-bit arithmetic.

Enter your data, then select calculate ipv6 prefix.

Technical reference: RFC 5952

1. Add your data

Enter your network data or load the worked example.

2. Choose the result

Calculate IPv6 prefix and review the result and assumptions.

3. Save it locally

Copy the result or download it for your engineering workflow.

About this tool

Use IPv6 Subnet & Address Calculator without an upload

Normalize IPv6 text and calculate prefix boundaries and exact address counts. Work locally without uploading network information.

The operation runs in the current browser tab. Tool input is not included in aggregate analytics, and the standalone download makes no analytics requests.

Network toolsDeveloper tools