Add (Subtract) Days to a Date

How to use the calculator to add or subtract days

Enter the initial date, choose whether to add or subtract, and type the number of days. When you press the "Calculate" button you get the result in calendar days, workdays (Mon-Fri) and workdays (Mon-Sat). For example, suppose you start on a Tuesday and add 7 days:

• Calendar days: this follows the civil calendar, Saturday and Sunday included. If you count every day in a row, those 7 days land on the following Tuesday.
• Workdays (Mon-Fri): only Monday to Friday count, like an office that closes on the weekend. Saturday and Sunday do not come off the total, so the same number of workdays lands further ahead: on the Thursday of the following week.
• Workdays (Mon-Sat): Saturday counts too and only Sunday is skipped, as in a six-day work week. In the same example you land on the following Wednesday.

How to add or subtract days from a date by hand

To add or subtract calendar days by hand you do not need a formula: you count the days on the calendar. The only thing to watch is the change of month and year:

1. Write down the day you start from: that is your initial date.
2. Decide how many days you want to add or subtract.
3. Count those days one by one, forwards or backwards.
4. If you go past the last day of the month, continue in the next month. If the year runs out, move to January of the next year.

An example: you want to add 10 days to 25 January. The 25th is not counted: the first day is the 26th. Through 31 January you move 6 days (26, 27, 28, 29, 30 and 31) and you still have 4 left. Those 4 are already in February: 1, 2, 3 and 4 February. That is the date. If you subtract 10 days from 4 February, you follow the same path backwards and return to 25 January.

Counting by hand works fine with a few calendar days. It gets messy as soon as you want workdays only — you have to skip Saturdays and Sundays — or when you add or subtract many days and cross several months. In those cases it is safer to use this calculator: it gives you the three dates with no errors and instantly.

Formula to add and subtract days in Excel

In Excel, to add days to a specific date, use the formula =DATE(YEAR(date), MONTH(date), DAY(date) + number_of_days). For example, to add 7 days to a date in cell A1, use =DATE(YEAR(A1), MONTH(A1), DAY(A1) + 7). This formula will automatically handle changes in month and year if needed.

To subtract days from a date, use the formula =DATE(YEAR(date), MONTH(date), DAY(date) - number_of_days). For example, to subtract 7 days from a date in cell A1, use =DATE(YEAR(A1), MONTH(A1), DAY(A1) - 7). Again, this formula will manage month and year changes correctly.

These formulas add or subtract calendar days: Excel only handles the change of month and year. They do not count workdays (they do not skip Saturdays or Sundays). For that, or for all three dates at once, use the calculator above.