ISO Fixed Duration Calculator
Add or subtract signed ISO day/time durations with exact millisecond arithmetic.
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How to use ISO Fixed Duration Calculator
Parse fixed days, hours, minutes, and seconds into BigInt milliseconds, add or subtract, then normalize to a signed ISO duration.
- Enter first iso duration, second iso duration.
- Check the model, units, and supported limits before calculating.
- Run the tool, inspect the result, then copy or download it.
Good to know
- Only PnDTnHnMnS, up to three fractional second digits, optional overall sign, magnitude ≤1e15 milliseconds. A day is exactly 24 hours. Calendar years/months, weeks, DST calendar arithmetic, and mixed component signs are excluded.
- Runs locally. Numeric inputs are bounded; floating-point output is approximate and rounded to 12 significant digits. Unsupported or non-finite calculations produce an error.
Common questions
How does ISO Fixed Duration Calculator calculate its result?
Parse fixed days, hours, minutes, and seconds into BigInt milliseconds, add or subtract, then normalize to a signed ISO duration.
What assumptions and boundaries apply?
Only PnDTnHnMnS, up to three fractional second digits, optional overall sign, magnitude ≤1e15 milliseconds. A day is exactly 24 hours. Calendar years/months, weeks, DST calendar arithmetic, and mixed component signs are excluded.
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