📅 Date Calculator
Add or subtract time from a date, or find the exact number of days, weeks, months, and years between two dates.
Choose Mode
Result
How the Date Calculator Works
This tool performs calendar-accurate date arithmetic. In "Add/Subtract" mode it moves forward or backward from a start date by a chosen number of days, weeks, months, or years. In "Days Between" mode it computes the exact span between two dates, including a full years/months/days breakdown.
Method
Days Between: difference = |dateB − dateA| in days, then converted to weeks/months/years
Frequently Asked Questions
How are months and years added to a date?
Adding months or years shifts the calendar month/year while keeping the day of month where possible; if the resulting month is shorter (e.g. adding a month to Jan 31), the date is adjusted to the last valid day of that month.
Does "days between" include both endpoints?
No — it returns the number of days separating the two calendar dates (e.g. Jan 1 to Jan 2 is 1 day), not an inclusive day count.
Can I calculate a date in the past?
Yes. Choose "Subtract" in Add/Subtract mode, or simply enter your two dates in any order in Days Between mode — the calculator handles both directions.