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IPv6 Subnet Calculator
Calculate the complete IPv6 CIDR range and exact decimal address count.
IPv6 address/prefix
ipv6-subnet-calculator.json
Browser only
Runs locally in your browser. Your files, pasted content and generated output are not uploaded. Reset clears this tool’s working data.
This tool needs JavaScript. If it does not load, refresh the page and try again.
How to use this tool
- Enter the displayed inputs, using the example values as a starting point. JSON inputs must use the documented shape.
- Choose Calculate result, inspect the complete report and download its JSON file.
- Change inputs and run again, or Reset to restore the examples and clear working output.
Examples
IPv6 address/prefix: 2001:db8::1/126
Limitations
- Hexadecimal IPv6 only, prefix 0–128. No embedded IPv4, zones or usable-host/broadcast assumptions.
- At most 100,000 UTF-16 units per text field and 400,000 UTF-8 bytes combined input; 4 MiB output and a 30-second local worker. Valid Unicode only. Tool-specific limits may be tighter.
- Decimal engineering calculations use finite JavaScript arithmetic. Structured record operations preserve exact JSON numeric tokens. Reports are local calculations or bounded format inspections, not a claim of external validity.
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