How to Calculate E-commerce Profit
8 min read · Updated 2026-06
Definition
E-commerce profit is what remains after every cost of selling online is subtracted from revenue. This formula works across all platforms.
Formula
E-commerce Profit = Revenue − Product Costs − Platform Fees − Payment Processing − Refunds − Shipping − Marketing − Operating Costs
Cost Breakdown by Platform
| Cost | Shopify | Amazon FBA | WooCommerce |
|---|---|---|---|
| Platform fee | $39+/mo | $39.99/mo | Free (host ~$25) |
| Payment processing | 2.9%+$0.30 | Incl. in referral | 2.9%+$0.30 |
| Referral | — | 15% avg | — |
| Fulfillment | You arrange | $3–$6/unit | You arrange |
| Total platform cost | 3–5% | 25–35% | 2–4% |
Common Mistakes
- Comparing revenue without adjusting for fees. $100K on Amazon ≠ $100K on Shopify. After Amazon's 30% take you keep $70K vs $95K on Shopify.
- Not factoring fulfillment costs. FBA is $3–6/unit. Self-fulfillment costs time. Calculate both.
- Forgetting Amazon auto-approves returns. Your return rate will be higher on Amazon.
FAQ
Is the profit formula the same for all platforms?
The core formula is the same: Revenue − All Costs = Profit. Costs differ. Shopify: 2.9% + $0.30. Amazon: 15% referral + FBA. WooCommerce: lower fees but hosting costs.
What is the biggest profit killer in e-commerce?
The combination of small leaks. 5% refund rate, $3.50 shipping subsidy, $120/month apps, 3% payment fees — together 15–20% of revenue.
Should I calculate profit per order or per month?
Both. Per-order for pricing. Monthly for business viability.
What about inventory costs?
Inventory ties up cash but is not a direct cost until sold. $20K in dead stock is $20K not working for you.
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