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Add days to a date

Add or subtract days from a date and find the resulting date and weekday. Includes weekends, holidays and leap years, with no registration.

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Set your data

Set your data

Choose a starting date and a whole number of days: positive to add, negative to subtract. The starting date is day zero. All calendar days count, including weekends and holidays.

Result

Enter your data and run the tool. Your result will appear here.

The values you enter stay on this page. Reloading or closing it clears them.

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How to use the tool

Enter a starting date and the number of days. The result shows the final date, weekday and unambiguous ISO YYYY-MM-DD format for copying.

Choose a start or arrival date on the calendar. Use the arrow keys or drag a highlighted date. The ±7 controls change the offset.

  1. Fill in these fields: Start date, Days to add or subtract.
  2. Select “Calculate” to obtain the result.
  3. Choose a starting date and a whole number of days: positive to add, negative to subtract.
  4. The starting date is day zero.
  5. All calendar days count, including weekends and holidays.

Method and principles

Final date = starting date + calendar days

Adding 0 days returns the same date. Adding 1 gives the following day. The starting date is not counted as day one. Use a negative number to move backwards.

Examples across months and leap years

January 1, 2026 plus 30 days is January 31, 2026. February 28, 2024 plus 2 days is March 1, 2024 because 2024 is a leap year. March 1, 2024 minus 1 day is February 29.

Practical example

Input
  • Start date: 2024-02-28
  • Days to add or subtract: 2
Result
2024-03-01

Calendar days versus working days

The calculation uses the proleptic Gregorian calendar for years 0001–9999, without reproducing historical national calendar reforms. Time zones and daylight saving do not affect the result.

To exclude weekends and holidays, use the working-days calculator. Legal or administrative deadlines may follow special rules that this date addition does not determine.

Result details

Result details
ParameterValue
Final ISO date2024-03-01
Day of the weekFriday
Days to add or subtract2

Limits and checks

Limits and checks
ParameterValue
Start date≥ 0001-01-01; ≤ 9999-12-31
Days to add or subtract≥ -3652058; ≤ 3652058

Frequently asked questions

Can I subtract days?

Yes. Enter a negative whole number, such as −10, to go back ten days.

Are weekends and holidays included?

Yes. All calendar days count. Use the separate working-days tool for exclusions.

Is the starting date included?

It is day zero: date + 0 stays the same, while date + 1 gives the next day.

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