Date Calculator

Date math is tricky. Months have different lengths (28-31 days), leap years add February 29, and weekends complicate business deadlines. Our Date Calculator handles all of it. Use it for project planning, contract deadlines, invoice due dates, pregnancy tracking, countdowns to events, and more. Two powerful modes: Add/Subtract Days (add or subtract days, weeks, months, or years to any start date) and Duration Between Dates (calculate exact time span between two dates with breakdown in years, months, days, total weeks, and total days). Business Days mode excludes Saturdays and Sundays automatically, with optional holiday exclusion for custom dates. The calculator handles month-end rollover correctly (January 31 + 1 month = February 28/29), leap years from year 1 to 9999, and supports multiple date formats (MM/DD/YYYY, DD/MM/YYYY, YYYY-MM-DD). Use for sprint planning, contract expiration tracking, statute of limitations calculation, countdown to vacation, pregnancy tracking, RSVP deadlines, semester length calculation, and warranty expiration tracking.

Date Calculator is optimized for fast browser-based use, so you can test multiple scenarios in seconds.