Ending Inventory Calculator

How to use this ending inventory calculator

What this calculator does

This calculator estimates the monetary value of inventory remaining at the end of an accounting period when you already know three amounts for the same period: Starting inventory, Net purchases, and Cost of goods sold. It also computes Goods available, Average inventory, and Inventory turnover. The model is an accounting identity, not a forecast of future demand, a stock-counting system, or a recommendation about how much inventory a business should hold. Inventory valuation rules still matter: the IFRS Foundation's IAS 2 overview explains how inventories are measured and recognized under IFRS.

When to use it

Use the calculator for a quick period-end reasonableness check, to reconcile an inventory roll-forward before preparing financial statements, to explain how a change in purchases or COGS affects the ending balance, or to estimate inventory turnover from a consistent set of accounting-period values. If COGS is not yet known, determine it from your accounting records and chosen valuation method before using this known-COGS model.

How to calculate

1. The calculator opens with a complete demonstration: $25,000.00 starting inventory, $30,000.00 net purchases, and $40,000.00 COGS. The first result is already calculated, and the Excel download is immediately available.
2. Replace each demonstration amount with the values for one consistent accounting period. Amounts accept U.S.-style numbers such as 25000, 25,000, or 25,000.00. A leading dollar sign is also accepted. Negative values, scientific notation, and ambiguous decimal-comma formats are rejected.
3. Read Ending inventory first, then use Inventory turnover, Goods available, and Average inventory for context. The flow table and allocation chart are generated from the same calculation model.
4. Select Download Excel to create a current-state workbook with Summary, Inputs, Breakdown, and Notes sheets. Select Reset to clear the demonstration values and results. After Reset, Excel export is disabled until all three required inputs are valid again.

Input guide

• Starting inventory is a required currency amount representing inventory on hand at the beginning of the period. Enter zero or a positive amount up to $1 quadrillion; a realistic example is $25,000.00. Increasing it raises goods available and, all else equal, raises ending inventory. A common mistake is mixing a beginning balance from one period with COGS from another.
• Net purchases is a required currency amount for inventory added during the period after applicable purchase returns or similar reductions. A realistic example is $30,000.00. Higher net purchases increase goods available and ending inventory when COGS is unchanged. Do not enter sales revenue here.
• Cost of goods sold is a required nonnegative currency amount recognized for the same period. A realistic example is $40,000.00. Higher COGS reduces ending inventory and normally increases turnover. COGS cannot exceed starting inventory plus net purchases in this model because that would imply negative ending inventory. The IRS Form 1125-A information page provides U.S. tax context for cost of goods sold reporting by applicable entities.

Output guide

Ending inventory is the primary currency result and equals goods available minus COGS. Goods available is the exact sum of starting inventory and net purchases. Average inventory is the simple average of starting and ending inventory used by this turnover calculation. Inventory turnover is COGS divided by average inventory and is displayed as a multiple, such as 2.00×. A higher multiple can indicate faster movement through inventory, but there is no universal target because turnover varies by industry, product shelf life, sourcing strategy, and seasonality. If average inventory is zero, turnover is shown as not defined rather than as an infinite value. The chart divides goods available into Cost of goods sold and Ending inventory; the table shows the same flow in accounting order.

Worked example

Using the startup values, goods available equals $25,000.00 + $30,000.00 = $55,000.00. Subtracting $40,000.00 of COGS leaves $15,000.00 of ending inventory. Average inventory is ($25,000.00 + $15,000.00) ÷ 2 = $20,000.00. Inventory turnover is then $40,000.00 ÷ $20,000.00 = 2.00×. Those figures match the first-open results, flow table, allocation chart, and the initial Excel workbook.

Learn more

For U.S. accounting-method context, the IRS maintains Publication 538, Accounting Periods and Methods. Reporting and valuation requirements can differ by jurisdiction and entity type, so use this calculator as an analytical aid and confirm formal reporting treatment with the applicable accounting standards and professional guidance.