Core formulas
The formulas to keep straight
sale price = regular price x (1 - discount)profit = sale price - unit cost - selling fees - ad costprofit lost = full-price profit - discounted profitdiscounted margin = discounted profit / sale priceHow do discounts affect profit?
Discounts affect profit by lowering the sale price while most costs stay the same. Product cost, labor, packaging, and fixed ad cost do not drop just because the buyer gets a discount.
That is why a 20% discount can remove 42.2% of profit in the example product.
Discount math was checked July 3, 2026.
Discount profit example, checked July 3, 2026
$60 regular price, $30 cost, 5% fee, no ad cost.
| Discount | Sale price | Profit | Profit lost |
|---|---|---|---|
| 0% | $60.00 | $27.00 | $0.00 |
| 10% | $54.00 | $21.30 | $5.70 |
| 20% | $48.00 | $15.60 | $11.40 |
| 30% | $42.00 | $9.90 | $17.10 |
How do ads change discount math?
Ads make discount math stricter because ad cost is another cost that must be paid from the smaller sale price. A product that survives a discount organically may fail when paid traffic is added.
Before running a promoted sale, calculate profit after discount and ad cost per sale.
If the discount is meant to improve conversion, the conversion lift has to be large enough to pay for the lost profit.
Discount plus ad cost, checked July 3, 2026
| Scenario | Profit | Comment |
|---|---|---|
| Full price, no ad | $27.00 | Baseline |
| 20% off, no ad | $15.60 | Profit reduced |
| 20% off, $5 ad cost | $10.60 | Less room for mistakes |
| 20% off, $12 ad cost | $3.60 | Very thin |
What is better than a flat discount?
A bundle is often better than a flat discount because it can raise order value while giving the buyer a reason to spend more. A free gift can also work if its cost is lower than the discount profit lost.
The best promotion is the one that protects profit while changing buyer behavior.
Do the profit check before choosing the promotion.
- Bundle related products.
- Use minimum order thresholds.
- Discount slow inventory only after checking cost.
- Avoid stacking discounts with paid ads unless the math works.
Decision table
Discount decision table, checked July 3, 2026
| Promotion | Use when | Risk |
|---|---|---|
| Flat percent off | Clearance or planned campaign | Can erase margin |
| Bundle | Products pair naturally | Needs cost check |
| Free gift | Gift cost is low | Can create packing work |
| Free shipping | Shipping cost is predictable | Can hurt heavy items |
| No discount | Demand is strong | May be the best profit choice |
Worked examples
Examples you can compare against your own numbers
Example: 20% off a $60 product
A product sells for $60, costs $30, and pays a 5% fee.
| Full-price profit | $27.00 | |
|---|---|---|
| 20% off sale price | $48.00 | |
| Discounted profit | $15.60 | |
| Profit lost | $11.40 |
Takeaway: The discount is 20% of price but 42.2% of profit.
Open this example in the discount profit calculatorAction checklist
Before you use this number in the real business
- 1Calculate full-price profit.
- 2Calculate sale price.
- 3Subtract cost, fees, and ads.
- 4Compare profit lost.
- 5Set a discount floor.
- 6Track whether conversion lift paid for the discount.
Common mistakes
Mistakes that make the answer look better than reality
FAQs
Questions people ask before making the decision
How do I calculate profit after a discount?
Use discounted sale price minus unit cost, fees, and ad cost.
Does 20% off reduce profit by 20%?
Usually no. In the example, 20% off reduces profit from $27 to $15.60.
What is a safe discount?
A safe discount is one that still leaves the minimum profit you are willing to accept.
Are bundles better than discounts?
Often yes, because bundles can lift order value instead of cutting every unit price.
Should I discount when running ads?
Only after checking profit after discount and ad cost per sale.
Sources and notes
Where the assumptions come from
General cost, margin, fee, and pricing workflow used in these examples.
Reference definition for gross margin and gross profit.
How FeeProofed checks formulas, examples, source notes, and calculator-backed guide content.