Calculation Issues

How to Calculate When Inventory Reaches Zero in Excel

Kushani Nimanthika Oct 14, 2026 869 views

Question details

The user needs to determine the specific month when warehouse inventory will be depleted, factoring in outgoing demand, incoming returned items, and scrapped units.

How to Calculate When Inventory Reaches Zero in Excel

Product: Excel
Device & OS: not provided
Scenario: Forecasting warehouse stock levels over time to anticipate inventory depletion and plan for future purchasing or repairs.
Observed behavior: A dynamic schedule is needed to project monthly ending stock balances continuously until the value hits zero.

Before you start

Ensure your inventory data is organized chronologically by month in columns, with dedicated rows for initial stock, total demand, usable returns, and additional purchases.

Solution 1Recommended

Create a Monthly Inventory Depletion Schedule

Use standard Excel formulas to build a rolling monthly schedule that subtracts demand and adds usable returns to find the zero-stock month.

This method involves calculating total demand, determining the number of usable returns after accounting for a scrap rate, and calculating the final ending stock for each month.

Calculate Total Demand

In your demand row (e.g., cell C7), sum up the individual demand metrics for the month using the formula =SUM(C2:C6).

Calculate Usable Returns

In your returns row (e.g., cell C8), calculate the returns arriving the following month minus the scrap rate (located in $B$11) using =ROUNDDOWN(C7*(1-$B$11),0). The ROUNDDOWN function ensures you only count whole units.

Calculate Ending Stock

In your ending stock row (e.g., cell C10), subtract the current month's demand and add returns and new purchases/repairs (C9) to the previous month's ending stock (B10). The formula will look like =B10-C7+C8+C9.

Project Future Months

Select the cells containing your new formulas (C7, C8, and C10) and drag the fill handle to the right across the subsequent monthly columns.

Create a Monthly Inventory Depletion Schedule

Identifying Depletion: Scan your Ending Stock row. The first month in which the value reaches zero or drops below zero is your depletion month.

Solution 2

Model Inventory with Power Query and Power Pivot

For complex scenarios with random rental dates and multiple items, use Excel 365's advanced data modeling tools.

Inventory Management with WPS

Manage Your Inventory Easily with WPS Spreadsheet

You can easily build complex inventory forecasting models and depletion schedules using WPS Spreadsheet. It fully supports standard functions like SUM and ROUNDDOWN for seamless calculations.

1. Open a New Workbook: Launch WPS Spreadsheet and create a new blank workbook to set up your inventory schedule.
2. Input Inventory Variables: Enter your initial stock, monthly demand, and scrap rate variables into a chronological grid layout.
3. Apply Rolling Formulas: Use formulas like =B10-C7+C8+C9 to dynamically calculate your monthly ending stock balances.
4. Drag and Forecast: Drag the fill handle across your monthly columns to project future inventory levels and find your zero-stock month.

Fully compatible with Microsoft Excel formulas and .xlsx filesFree and lightweight alternative for robust data analysisBuilt-in templates for warehouse and inventory management

microsoft office alternative - wps office

Frequently Asked Questions

How do I account for a scrap rate when calculating usable returns?

You can multiply your total returned items by the usable percentage (1 minus the scrap rate). Using the ROUNDDOWN function, such as =ROUNDDOWN(Returns*(1-ScrapRate),0), ensures you only count whole, usable items in your inventory.

What if returns arrive in the following month instead of the current one?

To account for delayed returns, offset your formula references. When calculating a specific month's ending stock, add the returns calculated based on the previous month's demand to accurately reflect the one-month delay.

Can I automatically highlight the exact month my inventory reaches zero?

Yes, you can use Conditional Formatting. Select your Ending Stock row, click Conditional Formatting > Highlight Cells Rules > Less Than or Equal To, enter 0, and choose a prominent fill color to instantly spot the depletion month.

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