How to Calculate True Ecommerce Profit (Not Just Revenue)

Most ecommerce sellers think they're more profitable than they are. That's because revenue is easy to see — it shows up as the order total in your dashboard. True profit is harder to calculate because it requires tracking seven or eight separate cost components per order. Here's the complete formula, with worked examples for eBay, Amazon, and Shopify.

The fees that catch sellers out

The costs most sellers forget or undercount:

• International buyer surcharge: eBay charges an additional 1.65% when the buyer is outside your domestic market. If 20% of your eBay sales are cross-border, this adds up fast.
• Promotional listing fees: eBay's Promoted Listings can add 5–15% of the sale price. Track this per SKU, not as a blended average.
• Returns cost: A 5% return rate means 1 in 20 items needs to be re-posted or refunded. This rarely appears in profit calculations.
• FBA fulfilment fees (Amazon): FBA fees include pick, pack, weight handling, and monthly storage. A heavy or oversized item can cost $6–$10 to fulfil through FBA — before the referral fee.
• Duty and import costs: If you import from overseas, import duty and shipping from supplier needs to be in your COGS — not treated as a one-off.

Amazon vs eBay: the fee difference

Amazon and eBay have different fee structures, which means the same product can have a very different margin on each platform:

• eBay: Final value fee (8–15% depending on category) + payment processing (approx 2%) + any promotional fees. Total: typically 10–17% of selling price.
• Amazon FBM (seller-fulfilled): Referral fee (6–15% depending on category) + no FBA fee. Total: typically 7–16% of selling price.
• Amazon FBA: Referral fee + FBA fulfilment fee ($4–$12 depending on size/weight) + storage fee. Total: typically 20–35% of selling price for standard items.

The implication: a product with a 30% gross margin sold on FBA may have only a 10–15% net margin after all Amazon fees. This is why sellers often discover their FBA margins are far lower than their eBay margins for the same product.

How to track this automatically

Manually calculating this per order is impractical at scale. The right approach is:

1. Use a platform that ingests your actual marketplace fee data (not estimated rates) from eBay and Amazon reporting APIs
2. Set a cost price (COGS) for every SKU in your system
3. Connect your shipping carrier to pull actual postage costs per order
4. Set your advertising spend as a percentage or fixed amount per SKU based on your campaign data

Platforms like Palvento do this automatically — pulling in actual fees from channel APIs, calculating true net profit per order, and surfacing your real margin by channel, SKU, and month. The goal is to know your real P&L in 30 seconds, not 30 minutes.

Palvento pulls in real fee data from your channels and calculates true net profit automatically. Most sellers discover their margin is 15–30% lower than they thought — and know exactly which listings to fix.