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Add or subtract days from a date

Choose a starting date, add or subtract any number of calendar days and get the resulting date and day of the week instantly.

FreeNo accountRuns in your browserNo dates uploaded

This calculation runs locally in your browser. ChronoBoxes does not receive the dates you enter.

Quick answer: find the date X days before or after another date

Enter a start date and a whole number of calendar days. The calculator moves forward or backward and returns the resulting date and weekday.

How date addition and subtraction works

This is calendar-day arithmetic. Weekends and public holidays count as normal days, so it is not a business-day or working-day calculator.

Timezone handling

The calculation uses the calendar date on your device and does not send the input to a server.

Common date calculations

  • 100 days from today.
  • 180 days after a project start date.
  • 365 days before an anniversary.
  • 1,000 days after a birth or relationship milestone.

Turn a date into a future moment

ChronoBoxes Tools and the ChronoBox creator are separate. If a date matters enough to calculate, you can optionally create a private message, add photos or video and keep it locked until that date.

Create a free ChronoBox →