Charm pricing is among the most widely used and least strategically understood tools in pricing practice. Most businesses use it because others use it, or because it feels like it should work. The research establishes both precisely why it works and precisely when using it damages the commercial position it is meant to support.

Thomas and Morwitz’s left-digit anchoring: the neurological mechanism

Thomas and Morwitz’s (2005) Journal of Consumer Research research established the cognitive mechanism behind charm pricing’s demand effect. The brain encodes numerical magnitude beginning with the leftmost digit before completing the full numerical representation. A price of £3.99 is encoded beginning with the 3 — producing an initial magnitude representation closer to £3 than to £4 — before the .99 is processed and the complete representation is formed.

The encoding sequence means that the psychological distance between £3.99 and £4.00 is substantially larger than the £0.01 arithmetic difference warrants. The £0.01 numerical difference produces a £1 psychological difference — because the initial encoding has already anchored to the 3 rather than the 4 before the decimal information arrives. The left digit is not merely the first digit processed; it disproportionately anchors the magnitude representation that the subsequent digits then adjust, insufficiently, around.

Manning and Sprott’s (2009) research confirmed the mechanism’s persistence and identified the conditions that modulate it: the left-digit anchoring effect is strongest when the left digit changes across the price boundary (£3.99 versus £4.00) and absent when it does not (£3.59 versus £3.60). The .99 ending’s commercial function is specifically the left-digit drop — not the .99 itself.

The Anderson-Simester field experiment: the effect outweighs the arithmetic

Anderson and Simester’s (2003) Quantitative Marketing and Economics field experiment across apparel catalogues produced the finding that most directly documents the mechanism’s commercial magnitude. The experiment tested the same dress at different price points, including £34 and £39. The £39 price — higher by £5 — produced higher demand than the £34 price when the £39 version used a .99-ending schema consistent with the catalogue’s promotional framing.

The demand effect of the charm pricing schema outweighed the rational arithmetic effect of the £5 price increase. The .99 ending activated the sale-price schema — the automatic association between .99 endings and promotional value — more powerfully than the actual price level influenced the willingness-to-pay calculation. The customer responding to the .99 schema was not making an arithmetic error; they were responding to a social signal about what the price means rather than a numerical signal about what it costs.

The finding has a specific commercial implication: charm pricing’s demand effect is produced by the schema activation — the sale-price association — rather than solely by the left-digit anchoring. This means the mechanism depends on the schema being intact: the .99 ending must reliably activate the “this is a good deal” association for the demand effect to follow.

The Stiving-Winer quality signal backfire: when charm pricing damages positioning

Stiving and Winer’s (1997) Journal of Consumer Research supermarket scanner data research established the counterpoint that makes charm pricing a strategic rather than a universal decision. The .99 ending activates the sale-price schema reliably — and the sale-price schema communicates price-conscious positioning, which means it communicates something specific about the product category and the customer relationship.

For price-sensitive segments in volume-oriented retail categories — supermarket goods, mass-market apparel, commodity software — the sale-price schema activation is commercially aligned with the positioning the brand is pursuing. The communication (“this is priced with your budget in mind”) matches the value proposition.

For premium, identity-expressive, or high-involvement categories — the luxury product, the professional service, the premium SaaS subscription, the quality-signal-dependent credence good — the sale-price schema activation contradicts the quality signal the price is supposed to send. The .99 ending tells the customer that the price is positioned for bargain-seekers, which undermines the quality inference that the price level was meant to communicate.

The Stiving and Winer supermarket scanner data showed that experienced retailers had already discovered this through practice: charm pricing was concentrated in standard-market products and absent in premium tier products within the same retail environment. The pricing convention had been calibrated to the quality-signal function through commercial experience before the research explained the mechanism.

Apple’s round number pricing as deliberate positioning

Apple’s consistent use of round numbers — £999, £1,299, £2,499 — rather than charm endings is the most prominent commercial implementation of the quality-signal account. The round number communicates confident premium positioning: this is what this is worth, stated without the hedging that the .99 ending implies. The absence of the .99 is itself a signal — it communicates that the price does not require the sale-price schema to make it acceptable.

The round number pricing decision is a quality positioning decision operating through the same price-quality heuristic mechanism that Rao and Monroe’s (1989) research established. The .99 ending communicates “we have priced this to feel like a good deal”; the round number communicates “we have priced this at its genuine value.” In categories where quality confidence is the primary purchase driver, the latter communication is more commercially aligned regardless of the left-digit anchoring effect that the .99 ending would otherwise produce.

The implication for premium positioning is specific: the charm pricing mechanism is a tool for segments where the sale-price schema activation is beneficial, and a liability for segments where the quality-signal integrity of the price is the mechanism that supports willingness to pay.

When charm pricing works and when it does not

The research converges on a specific framework for charm pricing deployment. The .99 ending produces demand improvement when: the product is in a volume or mass-market category where price-sensitivity is the dominant purchasing consideration; the customer segment is primarily motivated by value and budget optimisation; the competitive context rewards the sale-price signal; and the product is not positioned as a quality-signal-dependent purchase.

The .99 ending produces positioning damage when: the product category relies on price as a quality signal; the customer segment is identity-expressive, status-oriented, or quality-seeking; the brand is building a premium positioning that the sale-price schema undermines; or the product is a credence or experience good whose quality inference depends on price confidence.

The J.C. Penney case established in the previous article and Apple’s consistent round-number practice together bracket the commercial consequence of the choice: charm pricing is a positioning signal as much as a conversion mechanism, and using it in the wrong context trains the wrong customer expectation about what the product is and who it is for.

Books worth reading on this

Contagious: Why Things Catch On by Jonah Berger. Berger’s account of the social currency and identity signalling mechanisms that determine what customers communicate through their purchasing choices provides the most practically applicable available complement to the Stiving-Winer quality signal backfire mechanism. His specific account of how products signal identity and social position to the buyer’s reference groups maps directly onto the positioning damage that charm pricing produces in premium and identity-expressive categories.

If the dynamics described here are significantly affecting your wellbeing, speaking with a psychologist is the right next step. UK: Samaritans (116 123, free, 24/7). Mind (0300 123 3393). BACP: bacp.co.uk/search/Therapists. Crisis Text Line — text HOME to 741741 (US, UK, Canada, Ireland). International: internationaltherapistdirectory.com.

This article is for educational and informational purposes only. Sources: Thomas, M. & Morwitz, V. (2005), Penny Wise and Pound Foolish: The Left-Digit Effect in Price Cognition, Journal of Consumer Research, 32(1), 54–64. Manning, K.C. & Sprott, D.E. (2009), Price Endings, Left-Digit Effects, and Choice, Journal of Consumer Research, 36(2), 328–335. Anderson, E.T. & Simester, D. (2003), Effects of $9 Price Endings on Retail Sales: Evidence from Field Experiments, Quantitative Marketing and Economics, 1(1), 93–110. Stiving, M. & Winer, R.S. (1997), An Empirical Analysis of Price Endings with Scanner Data, Journal of Consumer Research, 24(1), 57–67. Rao, A.R. & Monroe, K.B. (1989), The Effect of Price, Brand Name, and Store Name on Buyers’ Perceptions of Product Quality, Journal of Marketing Research, 26(3), 351–357. Ariely, D. & Kreisler, J. (2017), Dollars and Sense, Harper. Berger, J. (2013), Contagious: Why Things Catch On, Simon & Schuster.