The verdict in three sentences
A promo code is a powerful but costly accelerator: on a 22% gross margin, a 10% discount destroys 45% of unit profit, which forces you to generate significant incremental volume to be profitable. Well-framed coupons (single use, cart floor, expiry) turn a discount into an acquisition or reactivation lever rather than a gift to customers who would have bought anyway. The golden rule: measure the real additional volume, not the number of coupons used.
The real cost of a discount on your margin
Many think a 10% discount costs 10%. Wrong: it comes off your margin, not your revenue. Here is the impact on a 22% gross margin.
| Displayed discount | Remaining unit margin | Profit destroyed | Additional volume needed to offset |
|---|---|---|---|
| 5% | 17% | -23% | +30% of sales |
| 10% | 12% | -45% | +83% of sales |
| 15% | 7% | -68% | +214% of sales |
| 20% | 2% | -91% | +1,000% of sales |
| Free shipping (2,500 FCFA) | variable | -1 profit by cart | depends on average cart |
The glass half full: a discount targeted at a first purchase can recruit a lifetime customer. The glass half empty: beyond 15%, you often need to triple volume just to avoid losing money.
Coupon types and anti-abuse rules
Not all coupons are equal. The table below compares 2026 mechanics and their safeguards.
| Coupon type | Recommended use | Typical redemption rate | Key anti-abuse rule |
|---|---|---|---|
| Percentage (-10%) | Reactivating dormant customers | 8–14% | Cart floor + 7-day expiry |
| Fixed amount (-2,000 FCFA) | Targeted acquisition | 10–16% | Single use per number |
| Free shipping | Raising average cart | 12–20% | Cart floor > 20,000 FCFA |
| First purchase (-15%) | Converting new visitors | 6–12% | One per new customer |
| Referral (-5% x2) | Viral growth | 4–9% | Validated after referred purchase |
Two non-negotiable rules: a cart floor (so the discount only applies above a profitable amount) and a short expiry date (to create urgency and limit exposure).
Mini case study
Mariama, who runs an accessories store in Dakar, launches a "-2,000 FCFA on 20,000 FCFA purchase" coupon, single use, valid 7 days. Usual average cart: 15,000 FCFA, 22% gross margin (3,300 FCFA). The floor pushes users' average cart to 24,000 FCFA. Gross margin on that cart: 5,280 FCFA, minus 2,000 FCFA coupon = 3,280 FCFA net margin, nearly identical to a normal cart, but with 9,000 FCFA more revenue per order. Across 120 redeemed coupons, she generates 1.08 million FCFA of additional revenue without degrading her unit margin. The coupon acted as a cart lever, not a profit destroyer.
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FAQ
Does a 10% discount really only cost 10%?
No. It comes off your margin, not your revenue. On a 22% gross margin, a 10% discount wipes out 45% of unit profit: you then need to sell 83% more just to compensate.
Which coupon type best protects margin?
Fixed amount with a cart floor (e.g. -2,000 FCFA on 20,000 FCFA). It pushes the average cart up, offsetting the discount, unlike an unconditional percentage that erodes every sale.
How do I prevent coupon abuse?
Single use per phone number, cart floor, short expiry (7 days) and exclusion of already-discounted items. These four rules block 90% of misuse.
Do promo codes attract genuinely new customers?
A "first purchase" coupon converts 6 to 12% of new visitors. The key is to reserve it for new numbers and measure retention after the first purchase, not just immediate volume.
What redemption rate should I target?
Between 8 and 14% depending on type. Too high a rate often signals a discount handed to customers who would have bought without it, i.e. a straight margin loss to rework.
Let's talk about your project. We configure your Wave/Orange Money coupons with floor, expiry and anti-abuse to protect your margin. WhatsApp +221 77 596 93 33.
Mohamed Bah
Fondateur, Kolonell
Passionate about digital and entrepreneurship in Africa, Mohamed has been helping Sénégalese businesses with their digital transformation since 2020. Founder of Kolonell, he believes every SME deserves a professional and accessible online présence.
