Add or Subtract Days Calculator
Add or subtract days or weeks from any date and get the resulting date with its day of the week. Calculates in your browser.
Resulting date
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How it works
The tool shifts your start date forward or backward by the number of days you enter (weeks are simply multiplied by seven). The result includes the day of the week, which is often the real reason people count days out.
result = start ± (amount × days-per-unit)
Dates are computed in UTC, so the answer never slips by a day around daylight-saving changes.
What this does
This calculator adds or subtracts a number of days or weeks from any date and returns the resulting date along with its day of the week.
How to use it
- Enter a starting date.
- Choose add or subtract.
- Enter the number of days or weeks.
- Read the resulting date and weekday.
How it works
Weeks are multiplied by seven before being applied. Month lengths and leap years are handled automatically, so the result is always a real calendar date.
result = start date ± (amount × unit)
Understanding your result
The weekday of the result is usually the point: a deadline that lands on a Saturday or a holiday normally has to move to the next working day, so read the day name before committing. This counts every calendar day, so when only working days should count, switch to the business-days tool instead of subtracting weekends by hand.
Example
90 days after 1 January 2026 is 1 April 2026, a Wednesday.
Sources & methodology
Last updated .
Frequently asked questions
Can I go backwards in time?
Yes, choose “subtract”, or enter the amount and pick subtract, to step the date earlier instead of later.
Does it handle weeks?
Yes. Switch the unit to weeks and the amount is multiplied by seven before being applied.
Is my data stored?
No. Everything is calculated locally in your browser.
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