How to Calculate Profit Before You Buy a Wholesale Product
By Hammad Kakli · 17 Oct 2026 · 5 min read
Many new wholesale sellers buy stock because the product is selling well. A good sales rank is not the same as profit. After Amazon’s fees, shipping and ads, a product that looks great can leave you with almost nothing. This guide shows the simple math I teach in the Wholesale course.
The four numbers you need
- Selling price: the price on the Amazon listing (use the Buy Box price).
- Product cost: what you pay your supplier for one unit.
- Amazon fees: the referral fee (a percentage of the price) plus the FBA fulfilment fee.
- Other costs: shipping to Amazon, prep, ads and returns.
Amazon’s free FBA revenue calculator shows the exact fees for your product, so you do not have to guess.
The formula
Profit per unit = Selling price - Product cost - Referral fee - FBA fee - Other costs
Margin = Profit ÷ Selling price × 100
ROI = Profit ÷ Product cost × 100
Worked example
These numbers are only an example. Fees change with category and product size, so check your own product.
| Item | Basic | With ads and shipping |
|---|---|---|
| Selling price | $30.00 | $30.00 |
| Product cost | $12.00 | $12.00 |
| Referral fee (15%) | $4.50 | $4.50 |
| FBA fee | $5.00 | $5.00 |
| Ads per unit | - | $2.00 |
| Shipping to Amazon | - | $1.00 |
| Profit per unit | $8.50 | $5.50 |
| Margin | 28.3% | 18.3% |
| ROI | 70.8% | 45.8% |
Same product, but the profit drops from $8.50 to $5.50 once you count ads and shipping. That is why the basic number alone is not enough.
You can try your own numbers in the FBA profit calculator.
Mistakes to avoid
- Using the lowest price on the listing instead of the Buy Box price.
- Forgetting ads, returns and shipping to Amazon.
- Ignoring how many other sellers share the Buy Box.
- Buying a large quantity before testing with a small order.
Quick checklist before you buy
- Fees checked in the FBA calculator
- Profit still positive after ads and shipping
- Margin and ROI meet your own target
- Supplier price and minimum order confirmed
- Started with a small test order
Frequently asked questions
What margin is good for wholesale?
It depends on your goals and costs. Many sellers set their own minimum for margin and ROI, then skip any product that falls below it.
Should I count my own time?
Yes, if you want the true picture. Time spent on sourcing, prep and customer messages is a real cost.
Amazon Account Manager, PPC Expert and E-Commerce Trainer.