Every margin you will ever quote to a buyer, a bank or yourself starts from one number: cost of goods sold. Get it right and gross margin, contribution margin and wholesale pricing all rest on solid ground. Get it wrong, usually by leaving something out, and every downstream figure is flattering fiction. Cost of goods sold, or COGS, is the direct cost of the products you sold in a period, and for a physical product brand it is both simpler and more slippery than it looks.
This guide covers what belongs in COGS, what does not, how to calculate it from your inventory, and the specific ways product brands get it wrong.
What goes into cost of goods sold
COGS is the cost of the units you sold, not the units you bought. For a brand that has products made and resells them, the direct costs per unit typically include:
- Product cost paid to the supplier or factory
- Packaging and labeling that ships with the product
- Inbound freight to your warehouse
- Duties, tariffs and customs fees on the inbound shipment
- Inbound handling such as receiving, inspection and labeling
- Direct labor if you assemble, finish or kit the product yourself
- Tooling, molds and samples amortized across the units they produced
If that list looks familiar, it should: per unit, it is your landed cost. Landed cost explained shows how to build that per-unit figure from the invoices. COGS is landed cost multiplied by the number of units sold in the period, adjusted for shrink, damage and write-offs.
What stays out of COGS
This is where product brands most often drift. The following are real costs, but they are operating or selling expenses, not COGS:
- Outbound shipping to customers or retailers
- Marketplace referral and fulfillment fees
- Advertising and promotions
- Warehouse storage fees after receipt
- Software, subscriptions and tools
- Salaries not tied to making units
- Rent, insurance, professional fees
Why the line matters: gross margin is revenue minus COGS. If you push selling costs into COGS, gross margin looks worse and channel comparisons get distorted. If you leave inbound freight and duties out of COGS, gross margin looks better than it is and you will price wholesale too low. The relationship between these layers is laid out in gross margin vs net margin.
The calculation
The textbook formula for a period is:
COGS = beginning inventory + purchases during the period, minus ending inventory
All three figures are at cost, meaning landed cost, not retail value.
A worked example for one quarter. You start the quarter with 2,000 units on hand at a landed cost of 6 dollars, which is 12,000 dollars. During the quarter you receive a new batch of 5,000 units at a landed cost of 6.50, which is 32,500 dollars of purchases. At the end of the quarter you count 3,500 units on hand.
The ending inventory value depends on your costing method. Using a weighted average, your 7,000 total units cost 44,500 dollars, which is about 6.36 per unit, so 3,500 remaining units are worth about 22,250 dollars.
COGS = 12,000 + 32,500 minus 22,250 = 22,250 dollars, for the 3,500 units sold.
Check it: 3,500 units at about 6.36 is about 22,250. The number ties out.
If you sold those units for 15 dollars each, revenue is 52,500 dollars, gross profit is 30,250 dollars and gross margin is about 58 percent. Now try the same quarter using the factory quote of 4 dollars as cost: COGS would show as 14,000 and gross margin as about 73 percent. That 15-point gap is entirely imaginary, and it is the gap that sinks brands who price wholesale from the supplier invoice.
Costing methods, briefly
When batches land at different costs, you need a rule for which cost leaves inventory when a unit sells. The common options:
- Weighted average blends all batches into one running cost per unit. It is simple and smooths out freight swings. Most small product brands should use it.
- First in, first out assumes the oldest units sell first, so COGS reflects older costs while inventory reflects newer ones. It matches how physical stock usually moves.
- Specific identification tracks the actual cost of each unit or lot. Practical only for low-volume, high-value products.
Pick one, apply it consistently, and tell your accountant which one you chose. Switching methods mid-year to make a quarter look better is how founders lose track of their real margin.
Per-unit COGS is what pricing needs
The period calculation is for your books. For pricing decisions you want a per-unit COGS, kept current, per SKU. That number feeds:
- Your wholesale price, via the margin formula in how to calculate wholesale margin
- Your minimum order quantity, which exists so each order clears a multiple of your per-order overhead on top of COGS
- Your channel comparison, since marketplace fees and wholesale discounts both come off a price that has to cover the same COGS
- Any deal evaluation, where a buyer's requested price minus per-unit COGS is the first number you look at
The wholesale margin calculator takes per-unit COGS as its first input and shows what a given wholesale price leaves you, next to what the same unit earns on a marketplace.
Shrink, damage and write-offs
Units that never sell still cost money, and they belong in COGS. Damaged units in transit, defective units you scrap, samples given away to buyers, units lost in a warehouse count: each one is a cost of selling the units that did make it to a customer. A brand that receives 5,000 units, scraps 100 and gives away 50 as samples has 4,850 sellable units carrying the full cost of 5,000.
Track these separately so you can see them, then fold them into COGS so your margin reflects them. Ignoring a few percent of shrink every quarter is a slow leak that never shows up on any single invoice.
Mistakes that distort COGS
- Using purchases as COGS. Buying 5,000 units in a quarter does not mean you sold 5,000. Inventory sits on the balance sheet until it sells.
- Excluding freight and duties. The single biggest cause of overstated gross margin among brands that import.
- Forgetting amortized tooling. A 2,000 dollar mold spread over a first run of 2,000 units is a dollar a unit that disappears if you ignore it.
- Mixing in marketplace fees. They are selling costs. Putting them in COGS makes your gross margin look terrible and hides how large they really are.
- Never counting inventory. Without a real count, ending inventory is a guess, and so is COGS.
- One COGS for all SKUs. Variants with different sizes, materials or packaging have different costs. Average them and you will overprice some and underprice others.
Building the habit
A monthly routine that takes an hour once it is set up:
- Update per-unit landed cost for any SKU that received a shipment.
- Roll the weighted average for that SKU.
- Record units sold by SKU from every channel.
- Multiply, add any write-offs, and you have COGS for the month.
- Compare gross margin by SKU to last month and to your pricing assumptions.
That last step is the payoff. A SKU whose gross margin drifted down three points is telling you something, freight, a tariff, a supplier increase, before it shows up as a cash problem. The comparison by channel that follows from here is the subject of unit economics for a product brand.
The short version
COGS is the direct cost of the units you sold: product, packaging, inbound freight, duties, inbound handling, direct labor and amortized tooling, with shrink and write-offs added. Selling costs stay out. Calculate it from inventory with a consistent costing method, keep a current per-unit figure per SKU, and let that number anchor every price you quote.
With COGS and margin solid, the remaining job is finding buyers who will pay your price. WholesalePilot finds the retail buyers, wholesalers and distributors that fit your product, verifies their emails, sends outreach in your name and books the calls.
Every margin you quote is only as honest as the cost underneath it.
Paste your product link and see which buyers are a fit, free, and start the conversation.