Add or Subtract Days

Easily calculate future or past dates with this free date calculator. Add or subtract days from any date, with instant results showing weeks and months. No login required.
 Subtract

About

Date Input

Select a start date using a calendar interface

Days Input

Enter the number of days to add or subtract

Add/Subtract Toggle

Switch between adding or subtracting days

Calculate Button

Compute the new date based on inputs

Result Display

Shows end date, weeks, and months between dates

Reference

Date arithmetic is a fundamental operation in various fields, from project management to financial planning. It involves manipulating date components (year, month, day) while accounting for varying month lengths and leap years. Modern programming languages often provide built-in date/time functionality to simplify these calculations, ensuring accuracy across different calendars and time zones.

Calculation

The date calculation process involves these steps:
1. Retrieve the start date and number of days from user inputs
2. Create a new Date object from the start date
3. Use the addDays() method to increment or decrement the date by the specified number of days
4. Display the resulting end date
5. Calculate and show the number of weeks (days / 7) and months (days / 30) between the dates

Frequently Asked Questions

What time zone is used for the calculations?
The dates are calculated based on your local computer's time zone.
How are weeks and months calculated?
Weeks are calculated by dividing the number of days by 7, and months by dividing by 30 as an approximation.
Is there a limit to the number of days I can add or subtract?
There's no stated limit, but very large values may cause issues due to JavaScript Date object limitations.
Can I calculate the duration between two specific dates?
No, this tool is for adding or subtracting days from a start date. Use a 'Date Difference Calculator' for that purpose.
Does the calculator account for leap years?
Yes, the built-in date functions used in the calculation automatically handle leap years.