Excel Date Calculations Using TODAY
A powerful tool to perform date arithmetic, find the duration between dates, and project future or past dates relative to today, just like in Excel.
The beginning of the period.
The end of the period. If ‘Use Today’ is checked, this will be today’s date.
What are Date Calculations in Excel Using Today?
In Microsoft Excel, dates are stored as sequential serial numbers, where January 1, 1900, is serial number 1. This system allows for powerful arithmetic operations directly on dates. “Date calculations in Excel using today” refers to using the dynamic `TODAY()` function as a reference point for these calculations. The `TODAY()` function automatically returns the current date every time a workbook is opened or recalculated. This is extremely useful for tracking project deadlines, calculating ages, determining the number of days until an event, or analyzing time-sensitive data without manually updating the date. By combining `TODAY()` with simple arithmetic or other date functions like `DATEDIF`, you can create dynamic, self-updating formulas for a wide range of applications.
The Formulas for Date Calculations
The core of Excel’s date calculation is simple arithmetic. Because dates are serial numbers, you can add or subtract days just like any other number. The `TODAY()` function provides a volatile, current date reference.
The most common formulas you will encounter are:
- Calculating Difference in Days: `=EndDate – StartDate`. For example, `=A2 – TODAY()` would find the number of days between the date in cell A2 and today.
- Adding Days to a Date: `=StartDate + NumberOfDays`. For example, `=TODAY() + 30` returns the date 30 days from now.
- Subtracting Days from a Date: `=StartDate – NumberOfDays`. For example, `=TODAY() – 90` returns the date 90 days ago.
- The DATEDIF Function: `=DATEDIF(StartDate, EndDate, “unit”)`. This powerful function calculates the difference in complete years (“y”), months (“m”), or days (“d”). It can also find the remaining months after subtracting full years (“ym”) or remaining days after subtracting full months (“md”), which is perfect for age calculations.
| Variable / Function | Meaning | Unit / Type | Typical Range |
|---|---|---|---|
| StartDate | The earlier date in a calculation. | Date (Serial) | Any valid Excel date (Post 1/1/1900) |
| EndDate | The later date in a calculation. | Date (Serial) | Any valid Excel date (Post 1/1/1900) |
| TODAY() | A function that returns the current date. | Date (Serial) | The current system date. |
| “y”, “m”, “d” | Unit specifiers for the DATEDIF function. | Text | “y”, “m”, “d”, “ym”, “yd”, “md” |
Practical Examples
Example 1: Calculating Project Duration
Imagine a project started on March 15, 2023, and you want to know how many days it has been running as of today.
- Input (Start Date): 2023-03-15
- Input (End Date): Today’s Date (via `TODAY()`)
- Formula: `=TODAY() – “2023-03-15″`
- Result: The calculator would show the total number of days elapsed since the project began.
Example 2: Finding a Future Deadline
You need to set a deadline that is exactly 90 days from today’s date.
- Input (Base Date): Today’s Date
- Input (Days to Add): 90
- Formula: `=TODAY() + 90`
- Result: The calculator would display the specific date that is 90 days in the future. This is a common method for calculating deadlines.
How to Use This Date Calculations in Excel Calculator
- Select Calculation Type: Choose whether you want to find the ‘Difference Between Two Dates’ or ‘Add/Subtract Days from a Date’.
- Enter Your Dates:
- For ‘Difference’, provide a ‘Start Date’ and an ‘End Date’. You can check the ‘Use Today’s Date’ box to automatically use the current date as the end date.
- For ‘Add/Subtract’, provide the ‘Base Date’ and the number of ‘Days to Add or Subtract’.
- Review the Results: The calculator instantly shows the primary result (e.g., total days or the new date).
- Analyze the Breakdown: The ‘Duration Breakdown’ table and the visual chart provide a detailed look at the time period in terms of years, months, and days, similar to what you might calculate with an advanced `DATEDIF` formula.
- Copy Your Data: Use the ‘Copy Results’ button to easily transfer the calculated data to your clipboard for use in Excel or other documents.
For further reading, an advanced Excel formula guide can provide more complex functions.
Key Factors That Affect Date Calculations in Excel
- Leap Years: Simple division by 365 can be inaccurate. True date functions and this calculator automatically account for leap years, ensuring precision over long periods.
- Excel’s 1900 Date System: Excel for Windows incorrectly assumes the year 1900 was a leap year. While this rarely affects modern calculations, it’s a known quirk of the system.
- Time Component: The `TODAY()` function returns only the date, with the time set to midnight. If you need the current time, the `NOW()` function should be used. Using `TODAY()` ensures calculations are based on whole days.
- Date Formatting: A common issue in Excel is a cell showing a serial number (e.g., 45878) instead of a date. This is a formatting issue; the underlying value is correct. You simply need to apply a ‘Date’ format to the cell.
- DATEDIF Function Quirks: The `DATEDIF` function is a “hidden” function in Excel, provided for compatibility with older spreadsheet programs. It works reliably for most cases but can have issues, especially with the “md” parameter, which is why we calculate days differently.
- Function Volatility: Because `TODAY()` is a volatile function, it will recalculate every time any cell in the worksheet is changed. This is great for dynamic dashboards but can slow down very large and complex spreadsheets. If you need a static date, you should type it in manually or use the `Ctrl+;` shortcut in Excel.
Understanding these factors can help you build more robust spreadsheets. Check out our resources on time tracking in spreadsheets for more information.
Frequently Asked Questions (FAQ)
It uses the browser’s built-in JavaScript Date object, which correctly accounts for leap years when calculating the difference between two dates. This is more accurate than simply dividing total days by 365.25.
`TODAY()` returns only the current date (e.g., 2026-01-25). `NOW()` returns the current date and time (e.g., 2026-01-25 14:30). For calculating day differences, `TODAY()` is typically preferred.
This happens because Excel stores dates as serial numbers. The number you are seeing is the correct underlying value. To fix this, simply change the cell’s number format to ‘Short Date’ or ‘Long Date’.
Yes, in Excel you can use the `NETWORKDAYS` function. It automatically excludes weekends and can optionally exclude a list of specified holidays. This calculator focuses on the total calendar day difference.
You would use the `DATEDIF` function three times: `=DATEDIF(BirthDate, TODAY(), “y”)` for years, `=DATEDIF(BirthDate, TODAY(), “ym”)` for months remaining after years, and `=DATEDIF(BirthDate, TODAY(), “md”)` for days remaining after months. Our calculator’s breakdown table provides this exact information.
The purpose of `TODAY()` is to be dynamic. If you want a static (non-changing) date in Excel, you can press the shortcut `Ctrl + ;` (semicolon) to insert the current date as a fixed value.
The most reliable method in Excel is `=DATEDIF(StartDate, EndDate, “m”)`, which calculates the number of full months between the dates.
While you can add days with simple math (e.g., `A1+30`), adding months or years is complex due to varying month lengths. In Excel, it’s best to use the `EDATE` function, like `=EDATE(StartDate, 12)` to add 12 months. Our calculator focuses on day-based calculations, which are the foundation of all date arithmetic.
To learn more, explore our guide on Excel date functions.