Count the days between two dates, or add and subtract days, weeks, months, and years from any date — leap years handled automatically.
In Days Between Dates mode, the calculator subtracts the earlier date from the later one and reports the exact number of days, plus the same gap expressed in weeks, in months and days, and in years. Leap years and varying month lengths are handled exactly, so February 28 to March 1 is one day in a common year and two in a leap year.
In Add / Subtract mode, it shifts a start date by any number of days, weeks, months, or years and returns the resulting calendar date along with its day of the week — useful for deadlines, notice periods, medication schedules, and project planning.
Whether you count the end date matters more often than people expect. From January 1 to January 3 is 2 days if you count elapsed days (exclusive), but 3 days if both endpoints count (inclusive). Contracts, rental periods, and prescriptions usually count inclusively; age and elapsed-time calculations count exclusively. The "include end date" toggle switches between the two.
If you want your exact age in years, months, and days, our age calculator is built for that; for hours and minutes between two clock times, use the time duration calculator.
Subtract the earlier date from the later one. This calculator counts the exact days between any two dates, along with the equivalent weeks, months, and years, handling leap years automatically.
Switch to Add / Subtract mode, pick a start date, choose add or subtract, and enter the number of days, weeks, months, or years. The calculator returns the resulting calendar date and its day of the week.
By default the end date is not counted (Jan 1 to Jan 3 is 2 days). Toggle "include end date" to count it, which is common for deadlines and rental periods.
When the target month is shorter, the date clamps to the last day of that month — adding one month to January 31 gives February 28 (or 29 in a leap year), matching how spreadsheets and most calendar apps behave.