CRO / Pricing
Discounting Strategy: When Discounts Help vs Hurt
// a discount is the easiest sale to make and the hardest to afford
By Fracto Solutions
October 28, 2026
The short answer
A discount is fast to run and expensive to afford. At a 40% margin a 20% cut needs unit sales to double just to hold gross profit, and more once fulfillment and payment costs are counted. Frequent discounting trains your existing customers to wait, though the same evidence shows it works differently on new ones.
+100%
-10.8%
+14 to 34%
When do discounts help, and when do they hurt?
They help for specific, time-bound goals: clearing old stock, acquiring a first-time buyer, hitting a genuine seasonal moment. They hurt when they become the default way to drive sales, because they erode margin and reset what your regular customers expect to pay.
Used surgically, a discount is a useful tool; used habitually, it is a slow leak. The problem is not any single sale, it is dependence. The alternatives that avoid it are in alternatives to discounting, and the execution detail is in running a sale without training customers to wait.
What's the real cost of a discount?
More than the percentage suggests, because it comes off margin rather than off price. If your gross margin is 40% and you cut 20%, you have given away half your margin, so you need unit sales to double just to make the same gross profit.
The arithmetic: the extra units needed to hold gross profit equal d / (m – d), where m is your gross margin as a share of price and d is the discount as a share of price. One assumption worth stating plainly, because getting it wrong inverts the answer: margin here is a percentage of price, not a markup on cost. A 30% markup on cost is a 23.1% margin on price, and at that margin a 20% discount is already selling below cost.
Include
At 30% margin
At 40% margin
At 50% margin
10% off
+50% units
+33% units
+25% units
20% off
+200% units
+100% units
+67% units
30% off
at cost
+300% units
+150% units
Extra unit sales needed to hold the same gross profit. At a 30% margin a 30% discount sells at exactly cost, so gross profit is zero at any volume; beyond that every extra unit destroys profit, which means volume makes it worse rather than better.
That table is the version everyone publishes, and it is optimistic. It counts only cost of goods. Ecommerce carries other per-unit variable costs, pick and pack, outbound shipping and payment processing, typically somewhere between 5% and 12% of price. Those belong in the denominator too:
Include
At 30% margin
At 40% margin
At 50% margin
10% off
+100% units
+50% units
+33% units
20% off
never
+200% units
+100% units
30% off
never
never
+300% units
Same calculation with 10% of price in other per-unit variable costs. At a 30% gross margin, a 20% discount can never break even on volume. Use your own fulfillment and payment costs rather than our illustrative 10%.
One correction to a line we used to run. “A discount is pure profit given away” is exactly right for every unit that would have sold at full price, and wrong for genuinely incremental ones, which still contribute as long as the discount is smaller than the margin. If fixed costs are already committed, incremental contribution drops to operating profit almost one for one. So the number that matters is not the sales lift, it is the incremental share, and the only way to know it is a holdout.
Does discounting really train customers to wait?
Yes for your existing customers, and the evidence is good. But the same field experiments found the opposite effect on new customers, and that distinction changes how you should use discounts.
The mechanism is reference prices. Winer (1986) established that choice depends on the gap between the price shown and an internally held expected price. Kalwani and Yim (1992) found that both promotion frequency and discount depth lower that expected price, and, importantly, that the absence of an expected deal hurts more than an unexpected deal helps. Blattberg, Briesch and Fox (1995) generalize it: deal frequency changes the reference price, and a lower reference price reduces the premium you can charge.
On the long-run cost, Mela, Gupta and Lehmann (1997) tracked 8.25 years of scanner panel data and found consumers became more price- and promotion-sensitive as promotion rose. Jedidi, Mela and Gupta (1999) put a number on it: a 5% increase in promotion frequency or depth reduced brand profit by 0.31% to 0.49%, negative across all four brands studied.
Now the part that is usually left out. Anderson and Simester (2004) ran three randomized catalog field experiments covering 56,466 established customers and more than 540,000 prospects, with discounts 40% to 47% deeper, followed for up to 28 months. Deep discounts reduced established customers’ future purchases by about 10.8% and increased new customers’ future purchases by 14% to 34%. The effect does not just vary in size, it changes sign.
So the rule is not “discounting trains customers to wait”. It is: discounting trains the people who already buy from you to wait, and can be a genuinely good acquisition tool for people who do not. That is a strong argument for targeting, which is the whole point of the next section. One scope caveat throughout: most of this literature is CPG scanner-panel data from the 1980s and 1990s, and the catalog experiments are the closest thing to ecommerce in it.
What are the alternatives to discounting?
Value adds, bundles, free-shipping thresholds, honest urgency, and loyalty rewards. Each can drive a sale without cutting the headline price, though the research on them is more conditional than the usual list suggests.
Bonus packs do often beat equivalent discounts: Chen, Marmorstein, Tsiros and Rao (2012) found consumers prefer them even when they are economically inferior. The mechanism is base value neglect, which is to say a consumer arithmetic error, and that is worth knowing before you build a strategy on it. It is also conditional: Mishra and Mishra (2011) found discounts win for indulgent products and bonus packs for virtuous ones, and Hardesty and Bearden (2003) found the size of the benefit itself changes which format wins. The full menu is in alternatives to discounting, including why “bundles protect per-unit margin” is not quite right.
How do I run a sale without training customers to wait?
Make discounts the exception, tie them to a real reason, keep them finite, and target them at new or lapsed buyers rather than everyone. That last part is where the Anderson and Simester split does real work.
There is also a nuance on predictability. Krishna (1994) found customers buy larger quantities on deal when deal timing is more certain, which supports making your calendar unreadable. But Swait and Erdem (2002) found inconsistent promotion patterns lower brand utility and increase choice uncertainty. The reconciliation is to be unpredictable in timing while staying consistent in how the brand presents itself, not to be chaotic. The tactics are in running a sale without training customers to wait.
What does the law require when I advertise a sale?
More than most merchants realize, and this is the fastest-moving area on the page. General information, not legal advice.
EU reference prices. Price Indication Directive Article 6a, applicable since 28 May 2022: any announcement of a price reduction must state the lowest price you applied in at least the previous 30 days. The CJEU confirmed in Aldi Sued (C-330/23, September 2024) that a percentage reduction must be calculated on that figure, not on a crossed-out list price.
US former prices. FTC 16 CFR Part 233 requires a bona fide former price offered on a regular basis for a reasonably substantial period, and §233.4 makes a “free” or two-for-one offer deceptive if you raise the price of the required purchase or cut its quantity. California §17501 adds a three-month prevailing-price test, and strikethrough class actions under it are constant: HP settled one for $4 million in April 2025 over models marked down continuously.
False urgency. Banned outright in the UK (DMCC Act Schedule 20 paragraph 7) and the EU (UCPD Annex I), with no need to prove harm, and CMA fines up to 10% of global turnover since 6 April 2025.
The practical consequence: an always-on sale section is not only a brand problem, it is the core legal theory in both the US class actions and the CMA’s lead case. Price with intent (see the pricing pillar) and keep records of why any reference price was genuine.
How do I measure whether a promotion actually worked?
By incremental gross profit, not the revenue spike. A sale almost always lifts revenue; the question is whether it made more profit than no sale would have, and the only honest way to answer that is a holdout.
Raw sales during a promotion are a misleading scorecard, because some of those buyers would have paid full price and every unit gave away margin. You will see “most of a promotion’s lift is just switching” quoted at around 75%; that figure was corrected. Van Heerde, Gupta and Wittink showed in 2003 that in unit sales terms only about 33% comes at the expense of other brands, with about 67% category expansion. Both figures measure cross-brand switching in CPG categories, which is not the question you actually have, which is what share of your discounted orders would have happened at full price. We found no published figure for that, and there will not be one, because it depends entirely on your store.
So hold out a random slice of the audience from the promotion and compare. Also watch the after-effects: did full-price sales dip before and after as customers timed their purchases? Tracking full-price conversion and margin over time, the same discipline behind attribution, tells you whether a promotion grew the business or moved demand around.
We run the discount math before the sale, and reach for margin-safe levers first.
We model what a discount actually costs in margin and the volume it needs to break even, push value-based alternatives where they’ll work, and when a discount is right, target it and measure it against its goal, so promotions build the business instead of quietly eroding it.
It’s the same measurement-first discipline behind our conversion optimization and analytics work, where we rebuild the buying path and measure the result .
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Frequently asked questions
Why are discounts more expensive than they look?
Because they come off margin, not price. At a 40% margin a 20% discount gives away half your margin, so unit sales must double to hold the same gross profit. Add fulfillment, shipping and payment costs of around 10% of price and the same discount needs a 200% increase, and at a 30% gross margin it cannot break even on volume at all.
Do frequent sales hurt my business?
For your existing customers, yes: reference-price research shows promotion frequency and depth both lower the price customers expect to pay. But Anderson and Simester’s field experiments found deep discounts reduced established customers’ future purchases by about 10.8% while increasing new customers’ by 14% to 34%. Target accordingly.
When does discounting make sense?
For specific, time-bound goals, targeted rather than blanket: acquiring a first-time buyer, winning back a lapsed one, or clearing stock. Judge each by whether it achieved that job profitably, using a holdout rather than the raw sales lift, since some of those buyers would have paid full price.
Is an always-on sale section a problem?
Legally as well as commercially. Continuously running promotions presented as time-limited are the core theory behind US strikethrough-pricing class actions, including HP’s $4 million settlement in April 2025, and behind the CMA’s lead enforcement case in the UK, where false limited-time claims are banned outright under Schedule 20 paragraph 7 of the DMCC Act.
What do I have to disclose when I run a sale?
In the EU, any announcement of a price reduction must state the lowest price you applied in at least the previous 30 days, and a percentage reduction must be calculated on that figure. In the US, a former price must be bona fide and offered on a regular basis for a reasonably substantial period, with California adding a three-month prevailing-price test.
Sources
Break-even arithmetic: this is algebra rather than a citation. With gross margin m expressed as a share of price and discount d as a share of price, the extra unit sales needed to hold the same gross profit are d / (m – d). Assumptions we state rather than bury: margin is a percentage of price, not a markup on cost (a 30% markup on cost is a 23.1% margin on price, and the formula breaks if you mix them); the discount uses the same base; unit cost is constant; the test holds absolute gross profit, so margin percentage always falls; and fixed costs are excluded, making it a contribution calculation. The second table adds other per-unit variable costs, which the first deliberately omits.
Reference prices and promotion expectations: Winer, “A Reference Price Model of Brand Choice for Frequently Purchased Products”, Journal of Consumer Research 13(2), 1986, established that choice depends on the gap between the observed price and an internally held expected price. Kalwani and Yim, “Consumer Price and Promotion Expectations”, Journal of Marketing Research 29(1), 1992, found that both promotion frequency and discount depth significantly lower the expected price, that there is a region of relative insensitivity around the expected price, and that the absence of an expected deal hurts more than an unexpected deal helps. Blattberg, Briesch and Fox, “How Promotions Work”, Marketing Science 14(3 Supplement), 1995, generalize that deal frequency changes the reference price and a lower reference price reduces the premium a brand can charge. https://journals.sagepub.com/doi/10.1177/002224379202900108
Long-run cost of promotion: Mela, Gupta and Lehmann, “The Long-Term Impact of Promotion and Advertising on Consumer Brand Choice”, Journal of Marketing Research 34(2), 1997: 8.25 years of IRI scanner panel data in a mature packaged-goods category, finding consumers became more price- and promotion-sensitive over time as promotion increased and advertising fell. Jedidi, Mela and Gupta, “Managing Advertising and Promotion for Long-Run Profitability”, Marketing Science 18(1), 1999: 691 households, 13,664 purchases over 8.25 years; a 5% increase in promotion frequency or depth reduced brand profit by 0.31% to 0.49%, uniformly negative across all four brands, with negative long-term effects about two-fifths the size of the positive short-term ones. Scope caveat: this is CPG scanner-panel data from single US markets in the 1980s and 1990s, not ecommerce. https://people.duke.edu/~mela/Jedidi_Mela_Gupta_1999.pdf
The effect reverses by customer type: Anderson and Simester, “Long-Run Effects of Promotion Depth on New Versus Established Customers: Three Field Studies”, Marketing Science 23(1), 2004. Three randomized catalog field experiments covering 56,466 established customers and 542,026 prospects, discounts roughly 40% to 47% deeper, followed for 22 to 28 months. Deep discounts reduced established customers’ future purchases by about 10.8% (6.89 against 7.67 units) while increasing new customers’ future purchases by 14% to 34%. This is the most rigorous direct-marketing evidence available and it contradicts the universal version of “discounting trains customers to wait”. https://www.kellogg.northwestern.edu/faculty/anderson_e/htm/personalpage_files/Papers/Long_Run_Effects_of_Promotion_Depth_on_New_versus_Established_Customers.pdf
How much of a promotion is incremental: Gupta, “Impact of Sales Promotions on When, What, and How Much to Buy”, Journal of Marketing Research 25(4), 1988, decomposed promotional elasticity as roughly 84% brand switching, 14% purchase acceleration and 2% stockpiling. That figure is widely misquoted. Van Heerde, Gupta and Wittink, “Is 75% of the Sales Promotion Bump Due to Brand Switching? No, Only 33% Is”, Journal of Marketing Research 40(4), 2003, showed that in unit sales terms only about 33% comes at the expense of other brands and about 67% is category expansion. Both measure cross-brand switching in CPG categories, which is not the ecommerce question of what share of your own discounted orders would have happened at full price. We found no published figure for that, which is why we recommend a holdout. https://doi.org/10.1509/jmkr.40.4.481.19387
Bonus packs versus discounts: Chen, Marmorstein, Tsiros and Rao, “When More Is Less: The Impact of Base Value Neglect on Consumer Preferences for Bonus Packs over Price Discounts”, Journal of Marketing 76(4), 2012, found in retail field experiments that consumers prefer bonus packs over economically equivalent and sometimes economically superior discounts, through base value neglect, moderated by numeracy. Mishra and Mishra, Journal of Marketing Research 48(1), 2011, found a strong moderator: discounts are preferred for vice products and bonus packs for virtue products. Hardesty and Bearden, Journal of Retailing 79(1), 2003, found the benefit level itself moderates which promotion type wins. So “value adds often convert as well as discounts” is conditional, not general, and we note that the documented mechanism is a consumer arithmetic error, which we would not build a strategy on. https://journals.sagepub.com/doi/10.1509/jm.10.0443
Advertising the sale itself: in the EU, Price Indication Directive 98/6/EC Article 6a, applicable from 28 May 2022, requires any announcement of a price reduction to state the lowest price applied in at least the previous 30 days, and the CJEU confirmed in Case C-330/23 (Aldi Sued, 26 September 2024) that a percentage reduction must be calculated on that figure. In the US, FTC Guides Against Deceptive Pricing, 16 CFR Part 233: a former price must be bona fide and offered on a regular basis for a reasonably substantial period (§233.1), and §233.4 makes a “free” or two-for-one offer deceptive if the seller raises the price of the required purchase or cuts its quantity or quality. California Business and Professions Code §17501 adds a three-month prevailing-price test, and perpetual-promotion class actions under it are filed constantly; HP settled one for $4 million in April 2025 over continuously marked-down models. https://eur-lex.europa.eu/eli/dir/1998/6/2022-05-28/eng and https://www.ecfr.gov/current/title-16/chapter-I/subchapter-B/part-233
Urgency and scarcity claims: false urgency is a blacklisted practice, banned per se with no need to prove harm. UK: Digital Markets, Competition and Consumers Act 2024, Schedule 20 paragraph 7, “falsely stating that a product will only be available for a limited time, or that it will only be available on particular terms for a limited time, in order to elicit an immediate decision”, plus paragraph 5 on false availability and paragraph 23 on “free” claims. CMA enforcement powers commenced 6 April 2025 with direct fines up to the greater of GBP 300,000 or 10% of worldwide turnover. EU: the same practices are blacklisted in Annex I of the Unfair Commercial Practices Directive. US: the FTC’s September 2022 dark-patterns report names the “baseless countdown timer”, “false limited time message”, “false low stock message” and “false high demand message” specifically, and private class actions are the larger live exposure. https://www.legislation.gov.uk/ukpga/2024/13/schedule/20 and https://www.ftc.gov/system/files/ftc_gov/pdf/P214800+Dark+Patterns+Report+9.14.2022+-+FINAL.pdf
Stated as Fracto’s position, not research: that occasion-based, finite, targeted discounts are the right default; that an always-on sale section is a mistake; and that clearance should be judged on net realisable value rather than on the break-even table above. The first two follow from the reference-price literature but are not themselves measured. The clearance point is accounting logic: once stock is genuinely dead the original cost is sunk, so selling below cost is frequently correct even though the break-even table calls it impossible.