Date Calculator
Calculated in your browser — we never store your dataVerified formulas with automated testing
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Date & Time
Common Calculations
Date Math Notes
- • Adding 1 month to Jan 31 = Feb 28 (or 29 in leap year)
- • Leap years: divisible by 4, except centuries unless divisible by 400
- • Julian Day starts counting from 4713 BC (astronomers use this)
- • Unix timestamp counts seconds since Jan 1, 1970
Sources & Methodology
Formula:
Result Date = Start Date ± Number of DaysDate addition/subtraction
Source: Gregorian calendar arithmetic
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