Calculating a 90-day period in Excel is not just about simple arithmetic but about applying that calculation in various business scenarios, from project planning to financial forecasting. Here are three different methods to calculate 90 days from a given date in Excel, each useful in different contexts.
Method 1: Using the EDATE Function
The EDATE function in Excel is specifically designed for date manipulation, making it ideal for adding or subtracting months or days from a date.
- Formula: =EDATE(A1,3)
- Where:
- A1: is the cell containing the start date
- 3: represents the number of months to add (3 months in this case, since 90 days is approximately one quarter of a year)
This formula will give you the exact date 90 days into the future, considering leap years and different month lengths.
Method 2: Using Simple Addition
If you want to calculate the exact number of days rather than a month-based approach, you can use basic arithmetic:
- Formula: =A1 + 90
- Where: A1 is the start date
This method adds 90 days directly to the date, which is straightforward but might not account for end-of-month variations or leap years.
Method 3: Using the WORKDAY Function for Business Calculations
To calculate 90 working days, which excludes weekends and optionally holidays, you can use the WORKDAY function:
- Formula: =WORKDAY(A1,90)
- Where:
- A1: is the start date
- 90: is the number of working days to add
This formula is particularly useful for project management, where you might need to know when a task will be completed, excluding non-working days.
| Method | Formula | Use Case |
|---|---|---|
| EDATE | =EDATE(A1,3) | Project deadlines, lease expirations |
| Simple Addition | =A1 + 90 | General 90-day forecasts, simple date calculations |
| WORKDAY | =WORKDAY(A1,90) | Business operational planning, excluding weekends and holidays |
Selecting the appropriate method depends on your specific business needs, whether you need to account for business days, exact calendar days, or a rough estimate based on months.
📅 Note: When using the WORKDAY function, remember to define a holiday list or ensure that it's relevant for your calculation to avoid inaccuracies in date calculations for holidays.
Each method offers a unique approach to adding 90 days to a date in Excel, providing flexibility based on what exactly your project or calculation requires. By understanding these functions, you can enhance your Excel skills, making your work more efficient and your data analysis more accurate. Whether you're managing project timelines, planning for financial quarters, or simply need to track a period, these methods will help you accomplish your objectives with precision.
Why should I use EDATE instead of just adding 90 days?
+The EDATE function accounts for the actual calendar structure, which is especially useful for dates that span across month or year boundaries. Adding 90 days directly does not account for different month lengths or leap years.
What happens if I need to calculate 90 days excluding specific holidays?
+Use the WORKDAY function with an additional argument to exclude a list of holidays. For example, =WORKDAY(A1,90,HolidaysList), where HolidaysList is a range of cells containing the dates of holidays.
Can Excel round up or down to the nearest month when calculating 90 days?
+Yes, when using the EDATE function. If you calculate 3 months from a date like January 15, it will take you to April 15. If you calculate from January 31, it would go to April 30 or May 1, depending on rounding rules or your Excel version.
