Date Arithmetic Calculators
Calculate add days to date, date and subtract days from date and other date arithmetic calculations.
All Date Arithmetic Calculators
Add Days to Date CalculatorAdd a number of days to a date to find the resulting calendar date and day of the week.Date CalculatorAdd or subtract a number of days from a date to find the resulting calendar date and day of the week.Subtract Days from Date CalculatorSubtract a number of days from a date to find the resulting calendar date and day of the week.
Date Arithmetic Guides
How Adding or Subtracting Days From a Date Is Calculated
Adding or subtracting days from a date is calendar-aware day-by-day arithmetic — correctly rolling over month and year boundaries, including February's leap-year length, rather than a simple fixed-length addition.
Read guideWhy a Date Calculation's Result Depends on Which Month It Lands In
Adding the identical 30 days to two different starting dates lands one result in a 28-day February and the other in a 31-day October — the same day count, landing in genuinely different-length months.
Read guide