What does this LIFO inventory calculator estimate?
This tool applies the last-in, first-out cost-flow assumption to a sequence of inventory purchases. It estimates LIFO cost of goods sold (COGS), ending inventory value, revenue, gross profit, gross margin, average cost per unit sold, and the difference between LIFO and FIFO COGS for the same purchase history. LIFO is an accounting convention: it determines which costs are assigned to sales and which costs remain on the balance sheet. It does not require the newest physical items to leave the warehouse first.
The default example contains three chronological batches: 2 units at $10, 5 units at $13, and 7 units at $15. Selling 10 units consumes all 7 units from the newest batch and 3 units from the second batch, producing $144 of LIFO COGS. The remaining inventory consists of 2 units at $10 and 2 units at $13, worth $46. At a $16 selling price, revenue is $160, gross profit is $16, and gross margin is 10%.
How should each input be used?
Purchase batches must be entered from oldest to newest. For every batch, enter the number of units acquired and the cost paid per unit. Units are required to be whole, nonnegative counts in this calculator. Unit cost is expressed in U.S. dollars and may include cents. A higher cost in a newer layer generally raises LIFO COGS when that layer is sold, while a higher cost in an older unsold layer raises ending inventory instead. Use “Add purchase batch” whenever the SKU has another distinct acquisition cost; remove a row when that layer should not be included.
Total units sold is the quantity assigned to expense. It cannot exceed the total quantity purchased. Increasing units sold moves more cost from inventory to COGS, working backward from the newest batch until the requested quantity is satisfied. A value of zero leaves all purchase cost in ending inventory. Selling price per unit drives revenue, gross profit, and gross margin only. It does not change COGS because inventory cost is based on purchase layers, not the selling price. A zero price is allowed and produces zero revenue; negative prices and costs are rejected.
How does the LIFO calculation work?
The model first totals every purchase layer. It then starts with the most recent batch and assigns as many units as possible to the sale. If the newest batch is insufficient, the remaining sale quantity moves to the next-newest batch. This continues until all sold units are assigned or inventory is exhausted.
Initial inventory cost = sum of each batch’s units × unit cost
COGS = sum of LIFO units sold from each layer × that layer’s unit cost
Ending inventory = initial inventory cost − COGS
Revenue = units sold × selling price
Gross margin = gross profit ÷ revenue
Calculations retain full precision and display currency to two decimals. The layer table is the audit trail: its COGS allocation must sum to the primary result, its ending values must sum to ending inventory, and each row’s sold plus remaining units must equal the units originally purchased.
How should the results, chart, and table be interpreted?
LIFO COGS is the purchase cost assigned to the units sold. A high value can reflect more units sold, higher recent purchase costs, or both. Ending inventory is the cost basis still carried as an asset after the sale. Under rising costs, LIFO often leaves older, lower-cost layers in ending inventory. Revenue is sales volume multiplied by selling price. Gross profit is revenue minus COGS; a negative result means the selling price did not cover the LIFO cost assigned to the sale. Gross margin expresses that profit as a percentage of revenue, while average cost sold shows COGS per unit sold.
The allocation chart divides original inventory cost into COGS and ending inventory. Its two shares always total 100% when inventory has positive cost. The LIFO-versus-FIFO comparison is informational: a positive figure means LIFO assigned more cost to the current sale than FIFO; a negative figure means it assigned less. The layer table identifies exactly which batches were consumed, which makes unusual results easier to trace.
What accounting limitations and compliance issues matter?
This calculator is best used for learning, scenario analysis, and a straightforward periodic LIFO illustration. Real accounting systems may need beginning inventory, freight and other capitalized costs, purchase returns, write-downs, multiple locations, perpetual transactions, and dollar-value LIFO pools. The Internal Revenue Service discusses inventory methods and adoption procedures in Publication 538, while the legal foundation for U.S. tax LIFO appears in 26 U.S. Code § 472.
Reporting frameworks differ. U.S. entities may be able to use LIFO when applicable requirements are met, but the IAS 2 inventory standard does not permit LIFO as a cost formula. Method selection can affect taxable income, financial ratios, comparability, and disclosures. Consult a qualified accounting or tax professional before adopting or changing an inventory method; this calculator does not provide accounting, legal, or tax advice.