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Date Calculator

Two tools in one: calculate the exact number of days between any two dates, or add and subtract days from a date to find a future or past date. Results include a full breakdown in years, months, weeks, and days.

Select dates

All calculations run in your browser — nothing is stored

How to use

  1. 1Choose a mode using the toggle at the top — "Days between dates" or "Add / subtract days".
  2. 2In "Days between dates" mode, enter a start date and an end date. The difference is calculated instantly in total days, and broken down into years, months, weeks, and days.
  3. 3In "Add / subtract days" mode, enter a base date and a number of days. Use a positive number to go forward in time, or a negative number to go backward.
  4. 4Use the quick-add buttons (+7, +30, +90, +365) to jump common intervals without typing.
  5. 5Click Reset to clear all fields in the current mode.

Why Use This Tool?

Date arithmetic is surprisingly tricky to do mentally — months have different lengths, leap years add a day, and converting between days, weeks, months, and years compounds the confusion. This tool handles all of that instantly, whether you are calculating a project deadline, a contract duration, a delivery window, or just satisfying curiosity about how many days until an event.

Frequently asked questions