Date Calculator
Add or subtract days from a date and calculate the number of days between dates.
How to use this calculator
Enter the requested values, then select Calculate. Results are processed locally in your browser for this static website.
Accuracy notes
Results may be affected by rounding, unit conventions and the assumptions shown by the calculator. Verify important calculations independently.
What this calculator solves
Add or subtract days from a date and calculate the number of days between dates. This page provides the interactive calculation together with a plain-language explanation so the result can be checked against the underlying method.
Science and formulae
Date arithmetic advances or subtracts calendar days while respecting month lengths and leap years; date differences are based on elapsed calendar days.
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