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Add/Subtract Date Calculator

Add or subtract days, weeks, months, or years from a date.

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Tool guide

Free Online Add or Subtract Date Calculator

Add or subtract calendar years, months, weeks, and days from a starting date. Enter non-negative amounts, choose the operation, and review the resulting readable and ISO date in your browser.

Steps

How it works

  • Choose the starting date.
  • Select Add or Subtract.
  • Enter the years, months, weeks, and days to apply.
  • Calculate, then copy or download the resulting date.

Highlights

Key features

  • Combines years, months, weeks, and days in one calculation.
  • Supports both future-date and past-date calculations.
  • Uses calendar operations for years and months.
  • Converts weeks to seven-day increments.
  • Shows a readable result and an ISO-style date.

Use cases

Common uses

  • Find a date several days or weeks from a starting point.
  • Calculate renewal or follow-up dates.
  • Move a calendar date backward by months or years.
  • Combine multiple date offsets in one operation.

Notes

Limitations to know

  • The numeric fields accept non-negative values; use the operation selector to add or subtract.
  • Years, then months, then weeks and days are applied in that order.
  • JavaScript calendar rollover can move end-of-month dates into the following month, such as adding a month to January 31.
  • Leap-day year adjustments follow browser Date rollover behavior.
  • The tool does not skip weekends or holidays and does not calculate time-of-day offsets.

FAQ

Frequently asked questions

5 answers
Can I add months and days together?

Yes. Enter values in multiple fields; the calculator applies years, months, then the combined weeks and days.

What happens when I add one month to January 31?

The browser's calendar rollover rules apply, so an invalid target day can roll into the following month.

How is February 29 handled?

Year and month changes use browser Date arithmetic, which can roll a leap-day result into a valid date in the target year.

Can I enter a negative amount?

The fields are designed for non-negative amounts. Choose Subtract when you want to move backward.

Are weekends skipped?

No. Weeks and days are calendar offsets, so weekends and holidays remain part of the calculation.

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