About
About Date Calculator
Date Calculator is a browser-based Gregorian civil-date calculator for two jobs: measuring the calendar interval between two dates and shifting a date by years, months, weeks, and days.
Technical model
Calculations use integer civil days rather than browser timestamps. No UTC offset, daylight-saving transition, timezone database, milliseconds, or time-of-day is part of the result.
Calendar units
Years and months are calendar-relative and therefore have variable lengths. Month-end calculations constrain to the last valid day of the target month. Weeks and days are exact ordinal-day shifts.
What stays separate
Business-day and holiday counting, countdowns, age and date-of-birth work, day-of-week-only tools, dated timestamps with time-of-day, and timezone-aware elapsed time remain separate jobs.