What is the formula for cost of goods sold?

The cost of goods sold formula is: Beginning Inventory + Purchases − Ending Inventory. The result is the cost of just the units that sold during the period. Modern ecommerce systems usually compute the same figure per sale (the perpetual method) for a live inventory value and margin.

How do you calculate cost of goods sold for an Amazon business?

Value each unit at its landed cost (supplier price plus freight, duty, and prep), then expense that cost only when the unit sells. Over a period, COGS equals beginning inventory plus purchases minus ending inventory. Keep Amazon fees and ad spend out of COGS as separate operating expenses.

How do you calculate COGS as a percentage of sales?

Divide COGS for the period by sales for the same period, then multiply by 100. The one thing to nail down is the denominator: pick either gross sales or sales net of refunds and use it every month, because switching between them moves the ratio by several points and makes your trend meaningless. Keep Amazon fees out of the numerator too, or you're measuring something else. There's no universal benchmark worth quoting, since a private-label brand and a wholesale reseller live in completely different ranges. Your own trend line is the useful comparison.

Do Amazon fees count as COGS?

Generally no. Referral fees, FBA fulfillment fees, and storage fees are selling and operating expenses, not the cost of the product itself. Including them in COGS distorts gross margin. Keep product (landed) cost in COGS and report platform fees on their own expense lines.

Is shipping included in cost of goods sold?

Inbound freight to get inventory to your warehouse or to Amazon is part of landed cost and belongs in COGS. Outbound shipping to the customer is a fulfillment expense, not COGS. Drawing that line correctly keeps your gross margin accurate.

What is the difference between COGS and inventory?

Inventory is the cost of stock you still hold, recorded as an asset on the balance sheet. COGS is the cost of stock that has sold, recorded as an expense on the income statement. A unit's cost moves from inventory into COGS at the moment it sells.

Should I use cash or accrual accounting for COGS?

Accrual, in almost every case where inventory is involved. Cash basis expenses stock when you pay for it, which makes buying months look terrible and selling months look inflated. Accrual matches each unit's cost to its sale, which is what makes monthly margins comparable and what lenders and buyers of your business expect to see.

Does QuickBooks calculate COGS for Amazon sellers automatically?

Not well on its own. QuickBooks can track items and post COGS, but it doesn't understand Amazon settlements, landed cost layers, or FBA inventory movements. Sellers typically pair it with a connector that posts summarized settlement journals and computes per-SKU COGS underneath, then reconciles the net deposit to the bank feed.

What should amazon accounting software do for COGS specifically?

Four things: capture landed cost per receipt (not just invoice price), apply a consistent costing method like FIFO or weighted average, post COGS automatically as units sell, and adjust for lost or damaged units including reimbursement offsets. BeanHawk is built around that flow; A2X and Link My Books are worth comparing on the same checklist, and a careful spreadsheet remains viable for small single-channel catalogs.

Glossary

What is COGS?

Cost of Goods Sold — the cost of the units you actually sold in a period.

COGS (Cost of Goods Sold) is the cost of the units you actually sold during a period, not the cost of everything you bought. The cost of goods sold calculation is the single most consequential number on an ecommerce profit and loss statement, because it sits directly between your sales revenue and your gross profit. Get COGS right and your margins, taxes, and inventory value are trustworthy; get it wrong and every profitability decision you make is built on sand.

The defining idea behind COGS is matching: a unit's cost only becomes an expense in the period that unit sells. Until then, its cost sits on the balance sheet as inventory, an asset. For Amazon and multichannel sellers, this matters intensely, because the timing of buying stock, shipping it to FBA, and finally selling it can stretch across months. COGS is what keeps the expense lined up with the sale that earned the revenue.

This entry covers the formula, what belongs inside it for a marketplace seller, how FIFO and weighted average assign costs, a worked quarter with hypothetical numbers, and the actual journal entries that move cost from the balance sheet to the P&L. It ends with the mistakes that show up over and over in seller books, because COGS errors are rarely exotic. They're the same five habits, repeated monthly.

The cost of goods sold formula

The standard formula for cost of goods sold is: beginning inventory, plus purchases during the period, minus ending inventory. In other words, COGS equals what you started with plus what you bought, minus what's left on the shelf. That remainder is what you sold, valued at cost. This is sometimes called the periodic method, and it's the cleanest way to understand the calculation conceptually.

The alternative is the perpetual method, where you record COGS at the moment of each sale by pulling the cost of that specific unit out of inventory. Perpetual is how most modern ecommerce systems operate, because it gives you a live inventory value and live gross margin instead of waiting for a period-end count. Either way the annual total should reconcile, the difference is timing and granularity, not the underlying math.

•COGS = Beginning Inventory + Purchases − Ending Inventory
•Beginning inventory: the cost value of stock you held at period start
•Purchases: the landed cost of stock received during the period
•Ending inventory: the cost value of stock still unsold at period end
•The result is the cost of only the units that actually sold

What belongs in COGS for an Amazon seller

COGS should capture the full cost to get a unit ready to sell, which is its landed cost: the supplier price plus inbound freight, duties, and any prep or labeling. It does not stop at the invoice price from your supplier. Leaving freight and duty out of COGS is one of the most common ways sellers overstate their gross margin and then wonder why the bank balance never matches the spreadsheet.

Just as important is what does not belong in COGS. Amazon's selling fees (referral fees, FBA fulfillment fees, storage fees) and your advertising spend are real costs, but they are operating expenses, not the cost of the product itself. Mixing them into COGS distorts your gross margin and makes it impossible to compare product economics cleanly. Keep product cost in COGS and platform/selling costs in their own expense lines so each layer of the cost stack stays visible.

•In COGS: supplier unit price, inbound freight, duties/tariffs, prep and labeling
•Usually below the line: Amazon referral and FBA fees, storage fees, PPC/ads
•On the balance sheet until sold: inventory not yet sold
•Recovered reimbursements: offset the COGS of lost or damaged units

FIFO vs weighted average: how unit cost is assigned

Because you buy the same product at different costs over time, you need a rule for which cost to expense when a unit sells. FIFO (First-In, First-Out) consumes your oldest cost layers first, which tends to reflect physical flow well and is widely used. Weighted average cost recalculates a blended per-unit cost every time you receive new stock, smoothing out price swings. Both are accepted methods; what matters is choosing one and applying it consistently.

For sellers, this choice drives both COGS and ending inventory value, especially when supplier prices or freight rates move. During cost inflation, FIFO expenses cheaper old units first, leaving a higher inventory value and a slightly lower COGS than weighted average would. The right method is the one your accountant and your software support, applied the same way every period. BeanHawk tracks landed cost per receipt so COGS is calculated automatically as units sell, instead of being reverse-engineered at year-end.

A worked example: one product, one quarter

Say you sell a single product and start the quarter holding 200 units that landed at $8.00 each, so beginning inventory is $1,600. All numbers here are hypothetical. In February you receive 500 more units, but your supplier raised prices and freight went up, so this batch lands at $9.00 each: $4,500 of purchases. Over the quarter you sell 550 units. At quarter-end you count 150 units on hand.

Run the periodic formula first. Under FIFO, the 550 units sold consume the 200 old units at $8.00 ($1,600) plus 350 new units at $9.00 ($3,150), so COGS is $4,750 and ending inventory is 150 units at $9.00, worth $1,350. Check it against the formula: $1,600 beginning plus $4,500 purchases minus $1,350 ending equals $4,750. Same answer from both directions, which is exactly the reconciliation your books should pass every period.

One more number falls out of that quarter for free. Say those 550 units sold at $22 each, so revenue is $12,100. To calculate COGS percentage you divide COGS by sales: $4,750 into $12,100 is about 39%. That's your COGS percentage of sales, and 100 minus it is gross margin, 61%. Watching the ratio month over month tells you more than watching COGS in dollars, because dollars go up in a good month and the ratio doesn't. It moves only when supplier price, freight, or your selling price actually move, which is the signal you want.

Now weighted average, for contrast. After the February receipt you held 700 units costing $6,100 total, a blended $8.71 per unit (rounded). COGS for 550 units is about $4,791, and ending inventory is about $1,309. Neither method is more "correct"; they just time the $6,100 of total cost differently. The trap is switching between them casually, or worse, using whatever number the spreadsheet happened to produce that month. Pick one, document it, and let the method (not the mood) decide.

How COGS gets posted: the bookkeeping treatment

Mechanically, COGS is a two-sided entry: debit Cost of Goods Sold, credit Inventory. When you buy stock, nothing hits the P&L at all; the purchase debits Inventory (an asset) and credits cash or accounts payable. The expense only appears as units sell. Most sellers post this monthly as a single summarized journal per channel, backed by SKU-level detail in a subledger, rather than posting cost on every individual order. Your ledger stays readable and your product detail stays queryable.

This is also where cash-basis bookkeeping quietly ruins seller financials. On a cash basis, a $20,000 inventory buy in March is a $20,000 March expense, so March looks catastrophic and the following months look artificially fat. Accrual accounting with proper COGS matching is what makes month-to-month margins mean anything, and it's the presentation lenders, tax preparers, and eventual acquirers expect. If you're doing amazon bookkeeping on a cash basis today, moving to accrual COGS is probably the single highest-value upgrade available to your books.

Tooling determines how painful this is. Generic ledgers don't know what a settlement or a landed cost is, so sellers pair QuickBooks or Xero with amazon accounting software that posts summarized settlement journals and carries per-SKU costs underneath. When you evaluate quickbooks for amazon sellers setups, or broader ecommerce accounting tools like A2X or Link My Books, ask three questions: where does landed cost live, does COGS post automatically as units sell, and can it show margin per SKU after fees? Proper amazon fba accounting also needs one more thing: when Amazon loses or damages units and reimburses you, the recovery should offset the written-off cost, not land in revenue as mystery income. A spreadsheet can do all of this for a small catalog; the software earns its keep when SKUs, channels, and cost layers multiply.

Edge cases: returns, bundles, and multichannel sales

Returns reverse COGS, but only sometimes. When a customer returns a sellable unit, the clean treatment reverses both sides of the sale: revenue comes back out, and the unit's cost moves from COGS back into inventory. When the return comes back damaged or unsellable, the cost stays expensed, either left in COGS or reclassified to a write-off line. Amazon complicates this by sometimes reimbursing you for returns it mishandles, and that recovery should offset the cost you already ate, not inflate revenue. Sellers who ignore return flows entirely overstate COGS in heavy-return categories by a margin that's anything but rounding error.

Bundles and multipacks need explicit cost mapping. If you sell a two-pack as its own SKU, its COGS is two units of the component's landed cost plus any bundling labor or packaging, and selling one bundle must decrement two units from component inventory. Skip that mapping and one SKU's margin looks fantastic while your stock counts drift.

Multichannel sellers have one more rule to enforce: a unit's cost is identical no matter where it sells. The same candle sold on Amazon, Shopify, or eBay carries the same landed cost into COGS; only the fees differ by channel. Run per-channel P&Ls with a shared cost pool, and never let each channel's tool invent its own version of the unit cost.

Common COGS mistakes

Bad COGS rarely announces itself. Margins just drift from reality until a tax return, a loan application, or a due-diligence request forces a recount. These are the recurring culprits.

•Expensing inventory when purchased (cash-basis habit), which whipsaws monthly profit and misstates the balance sheet
•Using supplier invoice price instead of landed cost, silently overstating gross margin on every sale
•Stuffing Amazon fees or ad spend into COGS, which blurs product economics against selling costs
•Blending unit costs across batches with no method, so neither FIFO nor weighted average describes your books
•Never adjusting for lost, damaged, or disposed units, leaving phantom inventory value on the balance sheet
•Booking reimbursements as revenue instead of offsetting the cost of the units Amazon lost
•Skipping period-end counts entirely, so the formula's ending-inventory term is fiction

Frequently asked questions

What is the formula for cost of goods sold?: The cost of goods sold formula is: Beginning Inventory + Purchases − Ending Inventory. The result is the cost of just the units that sold during the period. Modern ecommerce systems usually compute the same figure per sale (the perpetual method) for a live inventory value and margin.
How do you calculate cost of goods sold for an Amazon business?: Value each unit at its landed cost (supplier price plus freight, duty, and prep), then expense that cost only when the unit sells. Over a period, COGS equals beginning inventory plus purchases minus ending inventory. Keep Amazon fees and ad spend out of COGS as separate operating expenses.
How do you calculate COGS as a percentage of sales?: Divide COGS for the period by sales for the same period, then multiply by 100. The one thing to nail down is the denominator: pick either gross sales or sales net of refunds and use it every month, because switching between them moves the ratio by several points and makes your trend meaningless. Keep Amazon fees out of the numerator too, or you're measuring something else. There's no universal benchmark worth quoting, since a private-label brand and a wholesale reseller live in completely different ranges. Your own trend line is the useful comparison.
Do Amazon fees count as COGS?: Generally no. Referral fees, FBA fulfillment fees, and storage fees are selling and operating expenses, not the cost of the product itself. Including them in COGS distorts gross margin. Keep product (landed) cost in COGS and report platform fees on their own expense lines.
Is shipping included in cost of goods sold?: Inbound freight to get inventory to your warehouse or to Amazon is part of landed cost and belongs in COGS. Outbound shipping to the customer is a fulfillment expense, not COGS. Drawing that line correctly keeps your gross margin accurate.
What is the difference between COGS and inventory?: Inventory is the cost of stock you still hold, recorded as an asset on the balance sheet. COGS is the cost of stock that has sold, recorded as an expense on the income statement. A unit's cost moves from inventory into COGS at the moment it sells.
Should I use cash or accrual accounting for COGS?: Accrual, in almost every case where inventory is involved. Cash basis expenses stock when you pay for it, which makes buying months look terrible and selling months look inflated. Accrual matches each unit's cost to its sale, which is what makes monthly margins comparable and what lenders and buyers of your business expect to see.
Does QuickBooks calculate COGS for Amazon sellers automatically?: Not well on its own. QuickBooks can track items and post COGS, but it doesn't understand Amazon settlements, landed cost layers, or FBA inventory movements. Sellers typically pair it with a connector that posts summarized settlement journals and computes per-SKU COGS underneath, then reconciles the net deposit to the bank feed.
What should amazon accounting software do for COGS specifically?: Four things: capture landed cost per receipt (not just invoice price), apply a consistent costing method like FIFO or weighted average, post COGS automatically as units sell, and adjust for lost or damaged units including reimbursement offsets. BeanHawk is built around that flow; A2X and Link My Books are worth comparing on the same checklist, and a careful spreadsheet remains viable for small single-channel catalogs.

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