Every Ecommerce Cost to Track for True Margins
From payment fees to return allowances: a simple framework for tracking full contribution margin and ensuring your business is actually profitable.
When new sellers launch an ecommerce business, they usually calculate their profit margin like this:
Retail Price - Wholesale Cost = Profit
Unfortunately, this simple formula is the fastest way to run a business into the ground. In reality, ecommerce is death by a thousand cuts. Every platform, payment processor, and shipping carrier takes a piece of your pie before it ever hits your bank account.
To build a sustainable business, you must calculate your Contribution Margin. This means accounting for every single variable cost associated with a sale.
The 5 Hidden Costs You Must Track
Here is the complete framework for what you need to track.
1. Landed Cost (COGS)
This is the foundational cost of your product, sitting in your warehouse, ready to ship.
- Manufacturing Cost: The raw materials or wholesale price paid to the factory.
- Freight & Customs: The cost to ship the goods from the manufacturer (e.g., in China) to your fulfillment center, including import duties and tariffs.
2. Fulfillment & Shipping
Once a customer clicks “Buy”, how much does it cost to get the item to their door?
- Pick and Pack Fees: If you use a 3PL or Amazon FBA, they charge a fee just to put the item in a box.
- Packaging Materials: Custom boxes, tape, void fill, and inserts.
- Outbound Shipping: The actual postage cost (USPS, UPS, FedEx) to send the item to the buyer.
3. Platform & Payment Fees
The internet toll collectors.
- Marketplace Commission: If you sell on Amazon or Etsy, this is their 8% to 15% referral fee.
- Payment Processing: If you sell on Shopify, Stripe or PayPal will take roughly 2.9% + $0.30 per transaction.
4. Customer Acquisition Cost (CAC)
How much did you spend on marketing to get this one specific sale?
- Ad Spend: Total spend on Facebook, Google, or TikTok ads divided by the number of purchases.
- Marketplace Ads: Amazon PPC or Etsy Ads spend.
5. Returns & Allowances
This is the silent killer. If your return rate is 10%, you need to model that into every single successful sale.
- Return Shipping: Do you offer free returns? You pay the postage.
- Unsellable Inventory: If a returned item is damaged and cannot be resold, that entire product’s COGS must be written off.
The True Profit Formula
Once you have all these numbers, your true formula looks like this:
Retail Price - (Landed Cost + Fulfillment + Platform Fees + CAC + Return Allowance) = True Contribution Margin
If that final number isn’t high enough to cover your fixed costs (software subscriptions, salaries, warehouse rent), you need to either raise your prices or lower your costs immediately.
Pro Tip: Use our Master Profit Calculator to instantly model all of these costs in one place and see your exact contribution margin!