How to Calculate Number of Weeks Between Two Dates in Excel?

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Calculating the number of weeks between two dates in Excel is a common task in project tracking, payroll planning, HR reporting, academic schedules, and timeline analysis. Microsoft Excel provides multiple ways to calculate weeks using formulas, depending on whether you need whole weeks, partial weeks, or weeks based on working days.

In this guide, you will learn simple and accurate methods to calculate weeks between dates using Excel formulas.

Understanding How Excel Handles Dates

In Microsoft Excel, dates are stored as serial numbers. Each date represents the number of days since January 1, 1900. This makes it easy to calculate date differences using subtraction.

Example

If you subtract these values, Excel returns the number of days between dates, which can then be converted into weeks.

Method 1: Calculate Weeks Using Simple Date Subtraction

The easiest way to calculate weeks is to subtract the start date from the end date and divide by 7.

Formula

=(End_Date - Start_Date) / 7

Example Table

This method returns exact weeks, including decimals if the period is not a full number of weeks.

Key benefit:
Useful when you want precise week values, including partial weeks.

Method 2: Calculate Complete Weeks Between Two Dates

If you need only full weeks, you can combine date subtraction with the INT function.

Formula

=INT((End_Date - Start_Date) / 7)

Example Table

This removes decimal values and shows only completed weeks.

Best use case:
Project milestones, reporting periods, or contract durations where partial weeks are ignored.

Method 3: Calculate Weeks Using the DATEDIF Function

Excel includes a hidden function called DATEDIF, which is designed for date calculations.

Formula

=DATEDIF(Start_Date, End_Date, "d") / 7

This formula first calculates days between dates, then converts days into weeks.

Example Table

Why use this method:
It gives more control when working with day-based date calculations.

Method 4: Round Weeks Up or Down Using ROUND Functions

Sometimes you need to round weeks instead of keeping decimals.

Round Down Weeks

=ROUNDDOWN((End_Date - Start_Date)/7,0)

Round Up Weeks

=ROUNDUP((End_Date - Start_Date)/7,0)

Example Table

Practical uses:
Billing cycles, payroll estimation, subscription planning.

Method 5: Calculate Weeks Based on Working Days Only

If your calculation should exclude weekends, use NETWORKDAYS.

Formula

=NETWORKDAYS(Start_Date, End_Date) / 5

This method assumes 5 working days per week.

Example Table

Ideal for:
Office schedules, employee workload tracking, business timelines.

Method 6: Calculate Weeks Between Dates Including Specific Week Start

Some businesses calculate weeks based on week boundaries instead of exact days.

Formula

=(WEEKNUM(End_Date) - WEEKNUM(Start_Date)) + 1

Example Table

Note:
This method depends on Excel’s week numbering system, which may vary based on regional settings.

Method 7: Display Weeks and Remaining Days Together

You can show both weeks and leftover days using a combined formula.

Formula

=INT((End_Date - Start_Date)/7) & " Weeks " & MOD(End_Date - Start_Date,7) & " Days"

Example Output

Helpful for:
Human-readable timelines, reports, and dashboards.

Common Mistakes to Avoid

Incorrect Date Formatting

Dates stored as text will break calculations. Always format cells as Date.

Reversed Date Order

If the end date is earlier than the start date, Excel returns a negative value.

Ignoring Holidays

For business calculations, consider using NETWORKDAYS.INTL to exclude holidays.

Choosing the Right Method for Your Needs

Vaishvi Desai

Vaishvi Desai is the founder of Excelsamurai and a passionate Excel enthusiast with years of experience in data analysis and spreadsheet management. With a mission to help others harness the power of Excel, Vaishvi shares her expertise through concise, easy-to-follow tutorials on shortcuts, formulas, Pivot Tables, and VBA.