90 Business Days Calculator
Calculate 90 business days from any start date, excluding weekends and optional holidays
Calculation Results
How to Calculate 90 Business Days in Excel: Complete Guide
Calculating 90 business days (excluding weekends and holidays) is a common requirement for project management, legal deadlines, financial reporting, and contract obligations. While you can use our interactive calculator above, understanding how to perform this calculation in Excel gives you more flexibility and control over your data.
Understanding Business Days vs Calendar Days
Before diving into calculations, it’s important to distinguish between:
- Calendar days: All days including weekends and holidays (7 days per week)
- Business days: Typically Monday through Friday, excluding weekends and optionally holidays (5 days per week)
- Working days: Similar to business days but may vary by organization or country
For most professional contexts in the United States and many other countries, business days are considered Monday through Friday, excluding federal holidays.
Method 1: Using Excel’s WORKDAY Function
The simplest way to calculate 90 business days in Excel is using the WORKDAY function. This function automatically excludes weekends and can optionally exclude specified holidays.
Basic Syntax
=WORKDAY(start_date, days, [holidays])
start_date: The date from which you want to start countingdays: The number of business days to add (90 in our case)holidays: (Optional) A range of dates to exclude as holidays
Example Without Holidays
To calculate 90 business days from January 1, 2024 (excluding only weekends):
=WORKDAY("1/1/2024", 90)
This would return April 15, 2024 (the 90th business day from January 1).
Example With Holidays
To exclude specific holidays, first list them in a range (e.g., A2:A10), then reference that range:
=WORKDAY("1/1/2024", 90, A2:A10)
| Holiday | Date (2024) | Day of Week |
|---|---|---|
| New Year’s Day | January 1 | Monday |
| MLK Day | January 15 | Monday |
| Presidents’ Day | February 19 | Monday |
| Memorial Day | May 27 | Monday |
| Juneteenth | June 19 | Wednesday |
| Independence Day | July 4 | Thursday |
| Labor Day | September 2 | Monday |
| Columbus Day | October 14 | Monday |
| Veterans Day | November 11 | Monday |
| Thanksgiving | November 28 | Thursday |
| Christmas | December 25 | Wednesday |
Method 2: Using WORKDAY.INTL Function
The WORKDAY.INTL function offers more flexibility by allowing you to specify which days should be considered weekends. This is particularly useful for countries with different workweek structures.
Basic Syntax
=WORKDAY.INTL(start_date, days, [weekend], [holidays])
weekend: Specifies which days are weekends using a weekend number or string
Weekend Number Codes
| Number | Weekend Days |
|---|---|
| 1 | Saturday, Sunday |
| 2 | Sunday, Monday |
| 3 | Monday, Tuesday |
| 4 | Tuesday, Wednesday |
| 5 | Wednesday, Thursday |
| 6 | Thursday, Friday |
| 7 | Friday, Saturday |
| 11 | Sunday only |
| 12 | Monday only |
| 13 | Tuesday only |
| 14 | Wednesday only |
| 15 | Thursday only |
| 16 | Friday only |
| 17 | Saturday only |
Example for Standard Workweek
=WORKDAY.INTL("1/1/2024", 90, 1)
This is equivalent to the basic WORKDAY function, excluding Saturday and Sunday.
Example for Middle Eastern Workweek
In some Middle Eastern countries, the workweek is Sunday through Thursday with Friday and Saturday as weekends:
=WORKDAY.INTL("1/1/2024", 90, 7)
Method 3: Manual Calculation with NETWORKDAYS
The NETWORKDAYS function calculates the number of business days between two dates. You can use it in combination with date arithmetic to find a date 90 business days in the future.
Basic Syntax
=NETWORKDAYS(start_date, end_date, [holidays])
Implementation Steps
- Create a helper column with sequential dates starting from your start date
- Use NETWORKDAYS to count business days up to each date
- Find the first date where the count reaches 90
Example Implementation
In cell A1: 1/1/2024 (start date)
In cell A2: =A1+1 (drag down to create sequential dates)
In cell B1: =NETWORKDAYS($A$1, A1, $D$1:$D$10) (where D1:D10 contains holidays)
Find the row where column B first shows 90 – that’s your target date.
Common Challenges and Solutions
Challenge 1: Holidays Falling on Weekends
When a holiday falls on a weekend, some organizations observe it on the nearest weekday. Excel’s WORKDAY function doesn’t automatically handle this.
Solution: Manually adjust your holidays list to include the observed dates. For example, if July 4th (Independence Day in the US) falls on a Saturday, it might be observed on Friday, July 3rd.
Challenge 2: Different Holiday Schedules
Holidays vary by country and even by state/province within countries.
Solution: Maintain separate holiday lists for different regions. You can use named ranges in Excel to make this easier:
=WORKDAY("1/1/2024", 90, US_Holidays)
=WORKDAY("1/1/2024", 90, UK_Holidays)
Challenge 3: Partial Business Days
The WORKDAY function counts whole days. If you need to account for partial days (e.g., starting at noon), you’ll need additional calculations.
Solution: Add time components to your dates and use additional logic to handle partial days.
Advanced Techniques
Dynamic Holiday Lists
For recurring calculations, create a dynamic holiday list that automatically updates for the current year:
=DATE(YEAR(TODAY()), 1, 1) 'New Year's Day
=DATE(YEAR(TODAY()), 7, 4) 'Independence Day (US)
Conditional Formatting for Visualization
Use conditional formatting to highlight:
- Weekends in gray
- Holidays in red
- The target date (90th business day) in green
Creating a Business Day Calculator Dashboard
Combine multiple functions to create an interactive dashboard:
- Input cells for start date and number of business days
- A dropdown to select country/holiday set
- Output cell with the calculated end date
- A calendar view showing the period with weekends and holidays marked
Real-World Applications
Project Management
When creating project timelines, business day calculations help:
- Set realistic deadlines
- Allocate resources effectively
- Communicate expectations to stakeholders
Legal and Contractual Obligations
Many legal documents specify deadlines in “business days” rather than calendar days. Examples include:
- Response periods for legal notices
- Contract termination periods
- Payment terms (e.g., “payment due within 30 business days”)
Financial Reporting
Companies often have reporting deadlines based on business days:
- SEC filings (e.g., 10-K, 10-Q)
- Earnings releases
- Tax filing deadlines
Comparison of Methods
| Method | Pros | Cons | Best For |
|---|---|---|---|
| WORKDAY | Simple syntax, handles holidays | Limited to Sat/Sun weekends | Standard business week calculations |
| WORKDAY.INTL | Flexible weekend definitions | More complex syntax | Non-standard workweeks |
| NETWORKDAYS + helper | Full visibility into calculation | Manual setup required | Complex scenarios needing audit trail |
| VBA Custom Function | Complete control, can handle edge cases | Requires VBA knowledge | Enterprise solutions with special requirements |
Best Practices
1. Document Your Assumptions
Clearly note:
- Which days are considered weekends
- Which holidays are excluded
- How holidays falling on weekends are handled
2. Validate with Multiple Methods
Cross-check important calculations using:
- Different Excel functions
- Manual calendar counting
- Online calculators (like the one above)
3. Account for Time Zones
For international calculations, be mindful of:
- Different time zones affecting “end of day”
- Different holiday schedules
- Different weekend definitions
4. Consider Business Hours
If your calculation needs to account for specific business hours (e.g., 9 AM to 5 PM), you’ll need additional logic beyond standard business day functions.
Frequently Asked Questions
How do I calculate 90 business days backward from a date?
Use a negative number in the WORKDAY function:
=WORKDAY("4/15/2024", -90)
Can I calculate business days between two dates?
Yes, use the NETWORKDAYS function:
=NETWORKDAYS("1/1/2024", "4/15/2024")
How do I handle floating holidays (like “third Monday in January”)?
Create a helper function or use Excel’s date functions to calculate these dynamically:
=DATE(YEAR, MONTH,
15 + (8-WEEKDAY(DATE(YEAR, MONTH, 16))) '3rd Monday formula
)
Is there a way to calculate business hours instead of business days?
Excel doesn’t have a built-in function for business hours, but you can create a custom solution using:
- Time calculations
- Conditional logic for business hours
- Helper columns to track hour-by-hour