Date & Time Calculator

Add or subtract days, weeks, or years from a specific date. Calculate duration between dates.

New Date
Select a date

The resulting date falls on a --.

How to Calculate Dates Manually

Calculating dates can be tricky due to the varying number of days in months and leap years. Here are some tips:

Adding Days

To add days, simply count forward on a calendar. For example, adding 10 days to January 21st results in January 31st. If you add 15 days to January 20th, you cross into February.

Calculating Duration

To find the difference between two dates:

  • If the dates are in the same month, subtract the day numbers (e.g., 25th - 10th = 15 days).
  • If they are in different months, count the remaining days in the first month, add the full months in between, and add the days of the final month.

Our calculator handles these complexities automatically, including leap years and month lengths, to give you the exact date or duration instantly.