Date Calculator — Add Days & Find Differences

Date Calculator — Add Days, Weeks, Months to Any Date

Need to know how many days between two dates? Or what date it will be 90 days from now? This calculator handles both: date differences and date arithmetic. Useful for project planning, deadlines, and age calculations.

The calculator supports both calendar days and business days (excluding weekends). Add or subtract days, weeks, months, or years from any starting date. Results include a full breakdown in multiple time units so you can report durations in whatever format your project requires.

Date math is surprisingly tricky because months have different lengths and leap years add an extra day every four years. Adding one month to January 31 could mean February 28 or March 3 depending on the implementation. This tool uses calendar-aware arithmetic that handles these edge cases correctly.

Common uses include calculating contract end dates, determining payment due dates, planning delivery timelines, and counting days for legal notice periods. The business days mode is particularly useful for SLA calculations where only working days count.

For more specific date tasks, use our Date Difference Calculator for detailed breakdowns between two dates, or the Age Calculator to determine exact age from a birth date.