# How to Add Days to a Date in Excel (Step by Step)

To add days to a date in Excel, put the start date in one cell, the number of days in another, and write a formula that adds them together. Excel stores dates as serial numbers, so plain addition works and returns a real date you can format and sort. This guide shows the exact formula, a filled-down column, and the fixes for the errors people hit most.

## Quick Answer

- Type your start date in cell A2 and the number of days to add in cell B2.
- In cell C2, enter `=A2+B2` and press Enter. Excel returns the new date [1].
- Drag the fill handle down to copy the formula to the rows below.
- Use a negative number in column B to subtract days instead of adding them [1].
- Format column C as a date if it shows a five-digit serial number.

## Before You Start

Two things decide whether this works on the first try.

First, your start date has to be a real date value, not text. Excel treats a genuine date as a number, so `=A2+B2` can do arithmetic on it. If the date was typed as text, or pasted from another system with the wrong format, the formula returns an error or a strange result. A quick test is to change the cell format to General. A real date turns into a number like 45306. Text stays as text.

Second, the result cell needs a date format. Excel usually applies one automatically when it sees a date plus a number, but not always. If column C shows 45336 instead of a date, that is a formatting issue, not a calculation error.

If you want to build a fuller picture of how Excel handles dates, the guide on [Excel date formulas for adding, subtracting and formatting dates](/blog/data-analysis/excel-date-formulas-add-subtract-format) covers the underlying serial number system.

## Step by Step

1. Open your spreadsheet and click the cell that holds the start date. In the example below this is A2.
2. Click the cell next to it, B2, and type the number of days you want to add. Type a positive number to move forward in time, or a negative number to move backward [1].
3. Click the result cell, C2, and type the formula:

$$=A2+B2$$

4. Press Enter. Excel returns the new date.
5. Click C2 again, then drag the small square at the bottom right corner of the cell down over the rows you want to fill. Excel adjusts the row references automatically, so C3 becomes `=A3+B3` and so on [1].
6. Check the format of column C. If you see a number instead of a date, select the column, then use the number format dropdown on the Home tab to pick a date format.

That is the whole method. The formula is short because Excel does the calendar math for you, including month ends and leap years.

## Worked Example

The table below tracks four project start dates and the number of days each task takes. Column C adds the two and returns the finish date.

| | A | B | C |
|---|---|---|---|
| **1** | Start Date | Days to Add | New Date |
| **2** | `=DATE(2024,1,15)` -> displays 01/15/2024 | 30 | `=A2+B2` -> displays 02/14/2024 |
| **3** | `=DATE(2024,2,1)` -> displays 02/01/2024 | 45 | `=A3+B3` -> displays 03/17/2024 |
| **4** | `=DATE(2024,3,10)` -> displays 03/10/2024 | 7 | `=A4+B4` -> displays 03/17/2024 |
| **5** | `=DATE(2024,4,20)` -> displays 04/20/2024 | 90 | `=A5+B5` -> displays 07/19/2024 |

Column C uses `=A2+B2` and is filled down to return each new date.

Reading the results:

- C2 adds 30 days to 01/15/2024 and returns 02/14/2024. January has 31 days, so the count crosses into February.
- C3 adds 45 days to 02/01/2024 and returns 03/17/2024. This crosses a leap year February, which has 29 days in 2024.
- C4 adds 7 days to 03/10/2024 and returns 03/17/2024, a simple one-week jump.
- C5 adds 90 days to 04/20/2024 and returns 07/19/2024, crossing three month boundaries.

Notice that C3 and C4 land on the same date from different starting points. That is expected, and it is a good check that the arithmetic is right.

## Other Ways to Do It

The direct addition method is the fastest for a single number of days. Two other approaches cover different needs.

**Add days inside the formula.** If you do not want a helper column, put the number straight into the formula:

$$=A2+30$$

This returns the same result as `=A2+B2` when B2 holds 30. It is handy for one-off calculations but harder to audit later, because the number is buried in the formula.

**Add days, months, and years together.** When a schedule shifts by a mix of units, the DATE function combined with YEAR, MONTH, and DAY handles it in one formula [1]:

$$=DATE(YEAR(A2)+B2,MONTH(A2)+C2,DAY(A2)+D2)$$

Excel rolls over automatically when the month total passes 12. If MONTH returns 6 and you add 7, the result is 13, which Excel reads as January of the following year and adjusts the year accordingly [1].

**Add months only.** For monthly cycles, the EDATE function adds or subtracts whole months from a date [1]. It is the right tool when the interval is measured in months, not days.

If you would rather not write a formula at all, the [date calculator](/tools/date-calculator) adds days to a date and returns the result, which is useful for a quick check before you build the sheet.

## Troubleshooting

**The result shows a number like 45336.** The cell is formatted as General or Number. Select the cell or column, open the number format dropdown on the Home tab, and choose a date format.

**The result shows a date but the wrong one.** Check that the start date cell is a real date. Select it and look at the formula bar. If the formula bar shows the same text you see in the cell, Excel is treating it as text.

**You get `#VALUE!`.** One of the two cells contains text that Excel cannot convert to a number. This usually happens when a date was imported from another system. Re-enter the date or convert it with DATEVALUE.

**The formula returns a date far in the future.** The days cell probably holds a much larger number than you intended, or the start date is off by a year. Click the cell and read the value in the formula bar.

**Filling down gives the same date in every row.** The reference is locked. Check whether the formula uses `$A$2` instead of `A2`. Dollar signs freeze the reference so it never moves.

## Common Mistakes

- **Typing the date as text.** Writing "January 15" without letting Excel recognize it as a date breaks the arithmetic. Fix it by entering the date in a format Excel accepts, or by converting the text with DATEVALUE.
- **Leaving the result column formatted as a number.** The math is correct but the display is a serial number. Fix it by applying a date format to the column.
- **Using a locked reference when filling down.** A formula with `$A$2` copies the same start date into every row. Fix it by removing the dollar signs so the reference moves with each row.
- **Adding days to a date that already includes a time.** A cell holding a date and time returns a result with a time attached. Fix it by formatting the result as a date only, or by wrapping the formula in INT.
- **Forgetting that negative numbers subtract.** If you want an earlier date, type a negative number in the days column [1]. There is no separate subtract function needed.
- **Assuming every month has 30 days.** Excel uses the real calendar, so results differ from a rough 30-day estimate. Trust the formula, not the mental math.

## Limitations

Plain addition moves the calendar date forward by a fixed number of days. It does not skip weekends or holidays. If you add 10 days to a Friday, the result is a Monday, and Excel counts the weekend as part of the interval. For working-day intervals you need a different function, and the guide on [calculating working days in a year with NETWORKDAYS](/blog/data-analysis/calculate-working-days-in-a-year-excel) explains how that works.

The method also assumes your dates are stored as real date values. Spreadsheets exported from other systems often carry dates as text, and the formula fails silently or returns an error until you convert them. Excel's date system also has a lower bound, so very old dates can behave unexpectedly. For anything before the supported range, store the date as text and do the arithmetic elsewhere.

## Frequently Asked Questions

### How do I add days to a date in Excel without a helper column?

Put the number directly in the formula, like `=A2+30`. Excel returns the new date in one step. The trade-off is that the number is hidden inside the formula, so it is harder to change later or to audit when someone else opens the file.

### Can I add days to a date and skip weekends?

Not with plain addition. Plain addition counts every calendar day. Use the WORKDAY function instead, which takes a start date and a number of working days and returns a date that lands on a weekday. You can also pass a list of holiday dates so those are skipped too.

### Why does my formula return a number instead of a date?

The result cell is formatted as General or Number. Excel stores the answer as a serial number and only displays it as a date when the cell format says so. Select the cell, open the number format dropdown on the Home tab, and pick a date format.

### How do I subtract days from a date in Excel?

Use the same formula with a negative number. If B2 holds -15, then `=A2+B2` returns a date 15 days earlier [1]. You can also write `=A2-15` directly. Both approaches work because Excel treats dates as numbers.

### Does adding days to a date work across leap years?

Yes. Excel uses the real calendar, so February 29 is counted correctly in leap years. In the worked example above, adding 45 days to 02/01/2024 returns 03/17/2024, which reflects the 29-day February. You do not need to adjust anything for leap years.

### Can I add days to a whole column at once?

Yes. Enter the formula in the first result cell, then drag the fill handle down the column. Excel adjusts the row references for each row automatically. If you prefer, double-click the fill handle and Excel extends the formula down as far as the adjacent column has data.

## References

1. [Add or subtract dates | Microsoft Support](https://support.microsoft.com/en-us/excel/add-or-subtract-dates)

## Further Reading

- [Broman KW, Woo KH (2018). Data Organization in Spreadsheets. The American Statistician](https://doi.org/10.1080/00031305.2017.1375989)
- [Ziemann M, Eren Y, El-Osta A (2016). Gene name errors are widespread in the scientific literature. Genome Biology](https://doi.org/10.1186/s13059-016-1044-7)
- [Microsoft Support: Excel help and learning](https://support.microsoft.com/en-us/excel)
- [McCullough B, Heiser DA (2008). On the accuracy of statistical procedures in Microsoft Excel 2007. Computational Statistics & Data Analysis](https://doi.org/10.1016/j.csda.2008.03.004)
- [Abeysooriya M, Soria M, Kasu MS et al. (2021). Gene name errors: Lessons not learned. PLOS Computational Biology](https://doi.org/10.1371/journal.pcbi.1008984)

## Related Articles

- [Excel Date Formulas: How to Add, Subtract and Format Dates](/blog/data-analysis/excel-date-formulas-add-subtract-format)
- [How to Sort by Date in Excel (Step by Step)](/blog/data-analysis/how-to-sort-by-date-in-excel)
- [How to Get the Number of Days in a Month in Excel](/blog/data-analysis/days-in-month-excel)
- [Day of the Week Formula in Excel: TEXT, WEEKDAY and CHOOSE](/blog/data-analysis/day-of-week-formula-excel)
- [How to Calculate Working Days in a Year in Excel (NETWORKDAYS)](/blog/data-analysis/calculate-working-days-in-a-year-excel)