Calculator Tools/Date Calculator
Date Calculator
Calculate date differences and D-Day
Input
Result
Select a date
Frequently Asked Questions
Yes, all date calculations properly handle leap years (years divisible by 4, except century years not divisible by 400). February 29th is correctly included when calculating differences that span leap years.
When the end day is less than the start day, we borrow from the previous month. For example, January 31 to March 2 is 1 month and 2 days (not 1 month and -29 days). The calculation uses the actual number of days in each month.
This calculator shows calendar days, not business days. For business day calculations, you would need to subtract weekends and holidays from the total days. Total days are provided so you can make this adjustment if needed.
Date math can be tricky with months of different lengths. Subtracting 1 month from March 31 gives February 28 (or 29 in leap years), not a date in February with 31 days. The calculator handles these edge cases according to standard date arithmetic rules.
The date calculator works with date values only (year, month, day) without timezone considerations. The dates you enter and receive are treated as local dates. For timezone-aware time calculations, use our Timezone Converter tool.