The Psychology of Discounts
"20% off" and "$10 off" can mean the same thing — but one always feels bigger.
The Rule of 100: When to Use % vs $
Jonah Berger popularized the Rule of 100: for items under $100, a percentage discount looks bigger. For items over $100, the dollar amount feels larger. A $10 discount on a $50 item is 20% off — "20% off!" sounds more impressive than "$10 off." But $10 off a $200 item is only 5% — "$10 off" sounds better than "5% off."
Anchoring: The First Number Wins
When you see "Was $100, now $70," your brain anchors to the $100 first. The $70 feels like a steal — even if the product was never worth $100. Retailers inflate the "original" price to make discounts feel bigger. Studies show anchoring can increase willingness to pay by 20–40%.
Loss Aversion and Discounts
Losing $10 hurts about twice as much as gaining $10 feels good (Kahneman & Tversky). Discounts work by reframing spending as avoiding a loss: "You'll lose this 10% discount if you don't act now!" Limited-time offers exploit this by adding urgency to the fear of loss.
Why "10% Off" Is Psychologically Perfect
| Factor | Why 10% Works |
|---|---|
| Easy to calculate | Just move the decimal point — instant mental math |
| Feels substantial | Double digits trigger "real savings" perception |
| Credible | Not so big that customers suspect inflated prices |
| Sustainable | Sellers can absorb 10% without destroying margin |
Decoy Pricing
The decoy effect: a coffee shop offers Small ($3), Medium ($6.50), Large ($7). Nobody picks Medium — it makes Large look like a bargain. The "useless" option exists only to make another option look better. In discounts, showing a 5%, 10%, and 15% tier makes 10% the "sensible" middle choice.