Date Calculator

Add or subtract days, months and years from any start date and find the resulting date instantly.

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Quick Reference

Use this calculator to find deadlines, expiry dates, future appointments, or past event dates. Results account for different month lengths and leap years.

Period Days
1 week 7
1 month ~30
3 months ~91
6 months ~182
1 year 365

How to use?

  1. 1
    Choose a Start Date Pick the date you want to calculate from.
  2. 2
    Select Add or Subtract Choose whether to move forward or backward in time.
  3. 3
    Enter the Duration Fill in years, months, and/or days. Then click Calculate.

FAQ

Does it handle different month lengths?
Yes. The calculator uses JavaScript's built-in Date object, which correctly handles months with 28, 29, 30 or 31 days and automatically adjusts for leap years.
What happens when adding months crosses a month boundary?
For example, adding 1 month to January 31 gives February 28 (or 29 in leap years) — the last valid day of the resulting month. This follows standard date arithmetic.
Can I use this to calculate deadlines or visa expiry dates?
Yes. Enter today's date as the start, choose Add, and enter the validity period. The result shows the exact expiry date and the day of the week.

What Is a Date Calculator?

A date calculator adds or subtracts a given number of days, months, and years from a starting date to find the resulting date. It is useful for calculating deadlines, expiry dates, countdowns, billing cycles, and anniversary dates.

How to Add or Subtract Dates

To add time to a date: enter the start date, select Add, enter the years/months/days, and click Calculate. To go backward in time, select Subtract instead.

Handling Month Lengths and Leap Years

This calculator uses JavaScript's native Date object, which automatically handles varying month lengths (28, 29, 30, or 31 days) and leap years.

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