Discounts are the most powerful tool in retail and the most dangerous when misunderstood. A seemingly modest 20% discount on a product with 40% margins requires a 50% increase in unit sales just to break even on total profit. Most businesses underestimate how much additional volume is needed to offset reduced margins.
The Break-Even Sales Increase
Required Increase = Discount % / (Margin % − Discount %) With 40% margin and a 20% discount: 20 / (40 − 20) = 100% more sales needed. With 50% margin and 20% discount: 20 / (50 − 20) = 67% more sales needed.
| Margin | 10% Discount | 20% Discount | 30% Discount |
|---|---|---|---|
| 30% | +50% sales | +200% sales | Impossible* |
| 40% | +33% sales | +100% sales | +300% sales |
| 50% | +25% sales | +67% sales | +150% sales |
| 60% | +20% sales | +50% sales | +100% sales |
*A 30% discount on a 30% margin product means zero profit per unit regardless of volume.
Common Discount Types
BOGO (Buy One Get One)
BOGO 50% off is effectively a 25% discount when the customer buys two. BOGO free is a 50% discount on two units. This sounds generous but the margin impact is significant.
Stacked Discounts
Stacking 20% off plus an additional 10% off does NOT equal 30% off. It equals 28% off: the price after 20% becomes the base for the 10%. $100 → $80 → $72, not $70.
Volume/Tiered Pricing
Offering lower per-unit prices at higher quantities can increase total profit even with thinner margins, because fixed costs are spread across more units. This is the safest discounting strategy.
Model any discount scenario with the Discount Calculator.
Key Takeaways
- A 20% discount on 40% margins needs 100% more sales to maintain the same total profit.
- BOGO 50% off is a 25% effective discount on the combined purchase.
- Stacked discounts multiply, not add: 20% + 10% = 28% off, not 30%.
- Always calculate the break-even volume increase before running a promotion.
Frequently Asked Questions
What is the most profitable type of discount?
Volume/tiered pricing is generally the safest because it encourages larger orders while maintaining margin. Conditional discounts (buy 3 get 10% off) also perform well because they increase average order value. Blanket percentage-off discounts are the riskiest.
Is BOGO better than a percentage discount?
BOGO forces the customer to buy more units, which can increase total revenue even at lower margins. A BOGO 50% off (25% effective discount) is usually better for the business than a flat 25% off because it guarantees doubled unit volume.
How do I know if my sale was profitable?
Compare total profit (not just revenue) before and after the promotion. If you normally sell 100 units at $50 with 40% margin, your weekly profit is $2,000. A 20% discount needs 200+ units at $40 with 20% margin just to match that $2,000.