Date Calculator
Calculate date differences, add or subtract time periods, and perform various date calculations
Date Calculator
Date Difference
Results
Select dates and click "Calculate" to see the results
Understanding Date Calculations
Calendar Systems
Modern date calculations are based on the Gregorian calendar, which was introduced in 1582. Understanding leap years and calendar rules is essential for accurate date arithmetic.
Leap Year Rules
- • Divisible by 4: Usually a leap year
- • Divisible by 100: Not a leap year
- • Divisible by 400: Is a leap year
- • Example: 2000 is leap, 1900 is not
Business Days
Business day calculations exclude weekends and optionally holidays. Different countries and industries may have varying definitions of business days.
Standard Rules
- • Monday through Friday
- • Excludes Saturday and Sunday
- • May exclude national holidays
- • Varies by country/region
Common Date Calculations
Age Calculation
Calculate exact age in years, months, and days by comparing birth date to current or specified date.
Date Arithmetic
Add or subtract years, months, days from a given date while handling calendar boundaries.
Day of Week
Determine which day of the week a particular date falls on using algorithms or lookup.
Time Zones
Consider time zone differences when calculating dates across different regions.
Holiday Calculation
Calculate dates of moveable holidays like Easter, Thanksgiving, or other cultural celebrations.
Working Days
Calculate business days excluding weekends and holidays for project planning.
Applications
- • Project planning and scheduling
- • Financial calculations (interest)
- • Legal deadlines and contracts
- • Human resources (vacation, tenure)
- • Medical records and prescriptions
- • Historical research and analysis
Date Formats
- • ISO 8601: YYYY-MM-DD
- • US format: MM/DD/YYYY
- • European: DD/MM/YYYY
- • Unix timestamp: seconds since 1970
- • Julian day number
Common Issues
- • Leap year edge cases
- • Month-end date arithmetic
- • Time zone confusion
- • Calendar system differences
- • Daylight saving time
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