How to use the gross profit method inventory estimator
- Enter the inventory at cost at the start of the period and the purchases made during it, after returns.
- Enter net sales for the same period, after returns and discounts.
- Choose whether your rate is a margin on sales or a markup on cost, then enter the rate from your own past results for similar goods.
- Read the estimated cost of goods sold and the estimated ending inventory. The table shows every step, and the margin and markup are both given so you can check which one you meant.
Formula
goods available = beginning inventory + purchases
estimated cost of goods sold = net sales x (1 - gross profit rate on sales)
estimated ending inventory = goods available - estimated cost of goods sold
margin = markup / (1 + markup), and markup = margin / (1 - margin)
A margin is gross profit divided by sales. A markup is gross profit divided by cost. They describe the same profit but give different percentages, so the tool converts between them and shows both.
A shop that cannot count its stock
A store started the period with $100,000 of inventory and bought $400,000 more, so $500,000 was available to sell. Net sales were $600,000, and past results suggest a 40% margin on sales. Estimated gross profit is $240,000, estimated cost of goods sold is $360,000, and estimated ending inventory is $500,000 - $360,000 = $140,000. That 40% margin is the same thing as a markup on cost of 66.67%.
Now suppose the rate you know is a 25% markup on cost, with $80,000 of inventory, $320,000 of purchases and $480,000 of sales. A 25% markup equals a 20% margin, because 0.25 / 1.25 = 0.20. Cost of goods sold is $480,000 / 1.25 = $384,000, which matches $480,000 x 0.80, so ending inventory is $400,000 - $384,000 = $16,000.
When the gross profit method is used
The method gives a reasonable estimate when a physical count is not possible or not worth doing: after a fire or theft, for interim reports between counts, or as a check on a count that looks wrong. It leans on one assumption, that this period's gross profit rate matches the rate of the past. A change in product mix, a sale or a price change breaks that assumption.
If you want an estimate that responds to changes in price tags, the Retail Inventory Method Calculator uses the cost to retail ratio of the goods themselves. For a count-based figure, the COGS Calculator works from beginning and ending inventory.
Margin or markup
Mixing these up is the most common mistake. A product bought for $60 and sold for $100 has a 40% margin and a 66.67% markup. Entering 40 as a markup would treat the same product as selling for $84. The tool asks which one you have so the answer follows from your meaning.
Assumptions and limits
- The gross profit rate stays the same as in the past period you took it from.
- Purchases are entered net of returns, and freight in is included only if you add it to inventory cost.
- Net sales and purchases cover exactly the same period as the beginning balance.
- Shrinkage, spoilage and theft are not separated out, so any loss shows up as part of the estimated ending inventory.
- The result is an estimate for planning and a reasonableness check. It is not a substitute for a count or for professional accounting advice.
Frequently asked questions
Is the gross profit method allowed for annual financial statements?
It is mainly an estimating method for interim periods and for loss claims. Whether it is acceptable for a particular report depends on the rules that apply to you, so ask your accountant before relying on it.
What gross profit rate should I use?
Use the rate you earned in recent periods on similar goods, taken from your own records. A rate from a different product line or a different season can give a misleading ending inventory.
Why does the tool refuse some inputs?
If the rate and sales imply a cost of goods sold larger than the goods available, the ending inventory would be negative. That means the rate, the sales or the purchases are inconsistent, so the tool asks you to check them.
How do I turn a markup into a margin by hand?
Divide the markup by one plus the markup. A 50% markup becomes 0.5 / 1.5 = 33.33% margin. To go back, divide the margin by one minus the margin.