Date Calculator
A free tool that instantly calculates the days, weeks, and months between two dates and the date a given number of days before or after a date (D-day). All calculations happen in your browser, so the values you enter are never sent anywhere.
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Enter the dates and press Calculate to see the results.
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How to use
- Choose a calculation mode: date difference or add/subtract days.
- For date difference, enter the start and end dates; for add/subtract, enter the base date and number of days.
- Press "Calculate" to see the number of days or the resulting date.
Frequently asked questions
How do I count the days between two dates?
Subtract the start date from the end date. If you want to count both the start and end dates, add one day to the result.
How is D-day calculated?
Subtract today's date from the target date to get the days remaining. In the date-difference mode, set the start date to today to check the D-day.
Are the dates I enter sent to a server?
No. All calculations happen inside your browser, and the values you enter are not sent to any external server.