Date Calculator

Find the difference between two dates or add/subtract days, weeks, months, and years from a date.

How to Use the Date Calculator

Use "Difference" to find days between two dates, or "Add/Subtract" to find a future or past date.

Formula

Date difference = |Date2 − Date1| in milliseconds ÷ 86,400,000 (ms per day). Addition adjusts using JavaScript Date methods for accurate month/year handling.

Frequently Asked Questions

Does this account for leap years?

Yes. JavaScript's Date object correctly handles leap years and varying month lengths automatically.