Why does the price of insulin stay high even when pharmaceutical companies raise it? Why do airlines constantly change ticket prices? Why do luxury brand handbags sometimes cost more than the market expects and still sell out?

The answer to all of these questions involves the same economic concept: price elasticity. It is one of the most practically useful ideas in economics, and understanding it explains pricing decisions that otherwise seem arbitrary or counterintuitive.

Price elasticity was first formalized by Alfred Marshall in his 1890 work Principles of Economics — one of the foundational texts of modern economics. Marshall's insight was that the sensitivity of demand to price was not a fixed property of a good but varied with circumstances: time horizon, availability of substitutes, income level, and the narrowness or breadth of how the market was defined. Over a century later, his framework remains the analytical foundation of almost every pricing decision in business and every tax or subsidy decision in policy.

The Core Concept: How Sensitive Is Demand to Price?

Price elasticity of demand (PED) measures the relationship between a change in price and the resulting change in quantity demanded. Specifically, it tells you: if a product's price goes up by 1%, how much does demand (quantity purchased) change?

The formula is:

PED = % change in quantity demanded / % change in price

Because higher prices almost always reduce demand, the result is typically negative. Economists often use the absolute value to simplify discussion (so a PED of -0.5 is often discussed as simply "0.5").

Elastic vs. Inelastic

The critical threshold is 1:

  • Elastic demand (|PED| > 1): A 1% price increase causes a greater than 1% drop in demand. Price changes cause proportionally larger changes in quantity.
  • Inelastic demand (|PED| < 1): A 1% price increase causes a less than 1% drop in demand. Price changes barely affect how much people buy.
  • Unit elastic (|PED| = 1): Price and quantity change in exact proportion.
  • Perfectly inelastic (|PED| = 0): Price has no effect on demand whatsoever. Theoretical, but insulin for type 1 diabetics approaches this.
  • Perfectly elastic (|PED| = infinity): Even a tiny price increase destroys all demand. Also theoretical — approximately true for commodities on public exchanges where all sellers offer identical products.

| Elasticity Type | |PED| Value | What Happens When Price Rises 10% | |----------------|-----------|-----------------------------------| | Perfectly inelastic | 0 | No change in demand | | Inelastic | 0 to 1 | Demand falls less than 10% | | Unit elastic | 1 | Demand falls exactly 10% | | Elastic | 1 to infinity | Demand falls more than 10% | | Perfectly elastic | Infinity | Demand falls to zero |

What Determines Whether Demand Is Elastic or Inelastic?

Several factors systematically affect elasticity. Understanding them lets you estimate elasticity before collecting data.

Availability of Substitutes

This is the primary driver. If close substitutes exist, a price increase sends buyers to alternatives, making demand elastic. If no substitutes exist, buyers must pay whatever the price is.

Insulin for type 1 diabetes: Extremely inelastic. Patients will go into life-threatening ketoacidosis without it. There is no substitute.

Brand-name cola: Moderately elastic. Pepsi, store brands, and water are all substitutes. A large price increase on Coca-Cola causes many consumers to switch.

Gasoline broadly: Inelastic (-0.2 to -0.4). Over the medium term, consumers can switch to electric vehicles, public transit, or move closer to work — making long-run elasticity higher than short-run elasticity.

Whether the Good Is a Necessity or a Luxury

Necessities (food, housing, utilities, medicine) tend to be inelastic. Consumers buy them regardless of price. Luxuries (restaurant meals, jewelry, vacations) are elastic — consumers can delay or forgo them.

However, the distinction is not always intuitive. Tobacco and alcohol are considered necessities by dependent users, making them inelastic despite being widely considered luxuries. This is why tobacco taxes are a reliable revenue source for governments — the tax reduces consumption somewhat but not proportionally.

Estimates of cigarette demand elasticity in the academic literature range from approximately -0.3 to -0.5 in high-income countries (Chaloupka & Warner, 2000). This means a 10% increase in cigarette prices reduces consumption by only 3-5%. Governments have used this fact deliberately: tobacco taxes both generate revenue and modestly reduce smoking rates, particularly among younger and lower-income smokers whose elasticity is somewhat higher than average.

Time Horizon

Demand almost always becomes more elastic over time. In the short run, consumers cannot easily change habits or find alternatives. In the long run, they can.

When gas prices spiked in 2022, short-term demand was relatively inelastic — people had to get to work. Over the following 18 months, sales of fuel-efficient vehicles accelerated, and electric vehicle adoption increased. The long-run response is larger than the short-run response.

Economists distinguish the short-run price elasticity of gasoline (typically -0.2 to -0.3) from the long-run price elasticity (approximately -0.6 to -0.8) (Hughes, Knittel & Sperling, 2008). The long-run figure is two to three times larger because consumers have had time to adjust their vehicle choices, commuting patterns, and residential locations in response to sustained price changes.

Share of Income

Goods that represent a large share of consumer budgets tend to attract more price sensitivity. A 10% increase in rent prices is agonizing and behavior-changing for most renters. A 10% increase in the price of table salt barely registers — it is too small a fraction of any household's budget to think about carefully.

This is why economists sometimes distinguish between the income effect (lower real income from a price increase changes purchasing behavior) and the substitution effect (consumers switch to relatively cheaper alternatives). For small-budget items, the income effect is negligible and price changes are barely noticed.

Definition of the Market

This is a subtlety that matters enormously in practice. Broadly defined markets are more inelastic than narrowly defined markets.

"Food" is highly inelastic — people do not stop eating. "Restaurant meals at full-service sit-down establishments" is moderately elastic — people can cook at home or eat at fast food instead. "Upscale Italian restaurants in downtown Chicago" is highly elastic — there are many substitutes at every level of abstraction.

This definitional sensitivity is not just academic. In antitrust law, market definition determines competitive assessment. Regulators examining a merger between two firms must decide whether the relevant market is narrow (making the combined firm dominant) or broad (making it a small player). Price elasticity estimates — particularly cross-price elasticities — are central evidence in these determinations.

Real-World Elasticity Estimates

Academic economists and industry researchers have measured elasticity for many categories:

Product/Service Estimated PED Type Key Source
Gasoline (short-run US) -0.2 to -0.4 Inelastic Hughes et al. (2008)
Cigarettes (general) -0.3 to -0.5 Inelastic Chaloupka & Warner (2000)
Prescription drugs (chronic) -0.1 to -0.3 Highly inelastic Goldman et al. (2004)
Food (all categories) -0.1 to -0.2 Highly inelastic Andreyeva et al. (2010)
Restaurant meals -0.7 to -1.1 Slightly elastic Andreyeva et al. (2010)
Economy air travel -0.8 to -1.5 Elastic Gillen et al. (2003)
Luxury goods (broad) -1.2 to -2.0 Elastic BCG estimates
Specific brand within category -3.0 to -5.0+ Highly elastic Tellis (1988)

Note: Elasticity varies by country, income level, time period, and market structure. These figures are approximations from the academic literature.

A notable meta-analysis by Tellis (1988) examined 367 brand price elasticity estimates from existing literature and found a mean absolute elasticity of -1.76 across brand-level observations — substantially more elastic than category-level estimates, confirming the market definition effect described above. More recent work on food and beverage elasticities by Andreyeva, Long & Brownell (2010) in the American Journal of Public Health found broad consistency with earlier estimates, with soft drinks registering an elasticity of approximately -0.8 to -1.0 — notably higher than staple food categories.

Price Elasticity and Total Revenue

One of the most practically important implications of elasticity is its relationship to total revenue (price x quantity).

If demand is inelastic: Raising prices increases total revenue, because the percentage drop in quantity is smaller than the percentage increase in price.

Example: A drug with PED = -0.2 is priced at $100. Raise the price to $120 (20% increase). Demand falls by only 4% (20% x 0.2). If original demand was 1,000 units, new demand is 960 units. Original revenue: $100,000. New revenue: $115,200. Revenue increased despite lower volume.

If demand is elastic: Raising prices decreases total revenue, because the percentage drop in quantity exceeds the percentage increase in price.

Example: A restaurant dish with PED = -1.5 is priced at $20. Raise the price to $22 (10% increase). Demand falls by 15% (10% x 1.5). Original orders: 500/week. New orders: 425/week. Original revenue: $10,000/week. New revenue: $9,350/week. Revenue fell.

If demand is unit elastic: Total revenue is unchanged by price movements. This is a mathematical curiosity — raising prices neither helps nor hurts revenue.

"The strategic implication is clear: for inelastic products, price increases are largely free money. For elastic products, they require careful balancing against volume loss. This asymmetry drives almost every major pricing decision in business."

The revenue-elasticity relationship also illuminates one of the more counterintuitive observations in pharmaceutical pricing. When Eli Lilly, Novo Nordisk, and Sanofi raised insulin prices substantially between 2010 and 2020 — in some cases tripling or quadrupling list prices — patients with type 1 diabetes had no viable alternative. A 2019 study in JAMA Internal Medicine found that 25% of insulin-dependent diabetics reported rationing their insulin due to cost, with documented cases of preventable deaths from diabetic ketoacidosis in patients who could not afford adequate doses (Herkert et al., 2019). The inelasticity that generated revenue for manufacturers created direct health consequences for the least price-sensitive, most dependent users.

Cross-Price Elasticity: Complements and Substitutes

Cross-price elasticity of demand (CPED) measures how demand for product A changes when the price of product B changes:

CPED = % change in quantity of A / % change in price of B

Substitutes: Positive CPED

When the price of one good rises and demand for another good increases, they are substitutes. Examples:

  • Butter and margarine
  • Uber and Lyft
  • Android and iOS devices
  • Netflix and Hulu

A positive cross-price elasticity is evidence of competitive substitutability. The higher the number, the closer the substitutes — meaning they compete more directly.

This matters enormously for antitrust analysis. Courts and regulators use cross-price elasticity to define markets. If raising the price of Pepsi causes consumers to buy significantly more Coke, the two products are in the same market. This approach — the SSNIP test (Small but Significant Non-transitory Increase in Price) — is the standard methodology used by competition regulators in the US, EU, and most major jurisdictions to delineate relevant markets (Motta, 2004).

Complements: Negative CPED

When the price of one good rises and demand for another good falls, they are complements — used together. Examples:

  • Printers and ink cartridges
  • Coffee makers and coffee pods
  • Streaming services and internet subscriptions
  • Gaming consoles and game titles

A negative cross-price elasticity is the mathematical signature of a complementary relationship. This is why printer manufacturers historically priced printers cheaply and charged high margins on cartridges — low printer prices increase total printer demand, which increases cartridge demand. The profit extraction happens at the complement stage.

The gaming industry perfected this model. Sony, Microsoft, and Nintendo historically sold consoles near or below cost, making margins on game licensing fees. The console is essentially a loss leader for a long-term stream of game purchases — a strategy that only works because console and games are complements with a strongly negative cross-price elasticity. A console at $600 would sell far fewer units, dramatically reducing the addressable market for licensed games.

Income Elasticity: How Demand Changes with Wealth

Income elasticity of demand measures how demand changes when consumer incomes change:

YED = % change in quantity demanded / % change in income

Normal Goods (Positive YED)

Most goods have positive income elasticity — as people get richer, they buy more. Examples include restaurant meals, travel, and consumer electronics.

Luxury goods have high positive income elasticity (YED > 1). As incomes rise 10%, demand for luxury goods rises more than 10%. This is why the luxury sector is sensitive to economic cycles and why luxury brand penetration rises sharply with national GDP.

The global personal luxury goods market grew from approximately $80 billion in 1995 to over $380 billion by 2022 (Bain & Company, 2022), driven substantially by the growth of the Chinese middle and upper class — whose incomes rose faster than luxury prices, generating disproportionate demand growth. This is income elasticity operating at a macroeconomic scale.

Inferior Goods (Negative YED)

Inferior goods are goods for which demand falls as income rises. As people get richer, they buy less of these things. Examples:

  • Bus travel (substituted with cars as income rises)
  • Budget store-brand groceries (substituted with name brands)
  • Instant ramen (substituted with fresh food)
  • Fast food (partially — wealthier consumers eat at sit-down restaurants more often)

Understanding income elasticity matters for strategic planning. A business selling inferior goods grows during recessions and contracts during economic expansion. A luxury brand does the opposite. Planning accordingly requires knowing where on the income elasticity spectrum your products sit.

Interestingly, recession evidence shows the lipstick effect — demand for small luxury treats (lipstick, affordable indulgences) tends to increase during economic downturns as consumers forgo expensive luxuries but still seek occasional affordable indulgences. This suggests income elasticity is not a single number but varies along the income distribution, with middle-range products often seeing the most volatility.

How Businesses Use Price Elasticity

Dynamic Pricing

Airlines are the canonical example of dynamic pricing — adjusting prices continuously based on real-time signals about demand. An unsold seat on a departing flight has zero value; filling it at any positive price is better than flying empty. Airlines therefore drop prices as departure approaches if demand is below expectations, and raise them if demand is high.

Hotels, ride-sharing platforms, and concert ticketing use similar algorithms. The goal is to price each unit as close to the customer's maximum willingness to pay as possible — capturing consumer surplus that flat pricing leaves on the table.

American Airlines is credited with pioneering systematic yield management (revenue management) in the 1980s, initially as a response to competitive pressure from low-cost carrier People Express. By 1988, American estimated that its revenue management system generated over $1 billion in annual revenue above what flat pricing would have produced (Smith, Leimkuhler & Darrow, 1992) — a figure that has since grown with more sophisticated algorithmic approaches.

Price Discrimination

Price discrimination involves charging different prices to different customer segments based on their willingness to pay (which reflects their individual elasticity).

Examples:

  • Student and senior discounts: Students and seniors often have higher price elasticity (limited income) — charging them less increases total revenue without reducing prices for full-paying customers
  • Geographic pricing: Software is priced differently in India versus the United States, reflecting different income levels and competitive alternatives
  • Business vs. economy airline seats: The same seat position on the plane, priced dramatically differently. Business travelers (often on expense accounts, with less price sensitivity) pay for priority boarding, extra legroom, and status — all proxies for inelastic demand
  • Subscription tiers: Offering free, basic, and premium tiers allows customers to self-sort by willingness to pay

Third-degree price discrimination — the most common form — divides customers into identifiable groups with different elasticities and charges each group a different price. The welfare effects are ambiguous: consumer surplus is reduced for low-elasticity buyers but the practice may allow products to be offered at all in markets where a single price would not cover costs.

Promotional Pricing and Loss Leaders

Retailers use inelastic anchor products to build store traffic, then make margin on elastic products where they have pricing power. Supermarkets often sell milk and bread at thin margins (customers know the price and are sensitive to it) while making margin on prepared foods and specialty items where customers are less price-savvy.

Loss leaders — products priced below cost to attract customers — work precisely because the complementary or subsequent purchases are profitable.

Amazon's Kindle e-reader was reportedly sold near cost for years, with the expectation that Kindle owners would purchase significantly more digital books and other digital content — a complementary goods strategy whose success is supported by subsequent reports that Kindle owners spend more on Amazon overall than non-Kindle customers.

Value-Based Pricing

For business-to-business products, elasticity analysis supports value-based pricing — pricing based on the economic value delivered to customers rather than cost-plus formulas.

A software product that saves a company $500,000 per year can be priced at $50,000-$100,000 and still deliver massive value. The pricing is anchored to value delivered (which reduces the customer's effective elasticity, because the alternative — not buying — is more costly than a price increase).

Salesforce, ServiceNow, and similar enterprise software companies price primarily on value and have demonstrated over two decades that customers with low price elasticity (high switching costs, high value delivered, no close substitutes) can sustain prices far above marginal cost of production.

Price Elasticity and Public Policy

Taxation

Governments use elasticity estimates to design taxes that achieve their goals. If the goal is revenue maximization, taxes should fall on inelastic goods — consumers will keep buying regardless of price. If the goal is behavior change (reducing consumption of harmful goods), taxes should fall on goods with higher elasticity — or on populations whose elasticity is higher (typically younger, lower-income consumers for tobacco and alcohol).

Sugar taxes are a contemporary policy application. The UK's Soft Drinks Industry Levy (introduced 2018) found that manufacturers reformulated products to avoid the tax — reducing sugar content significantly — rather than simply passing the tax to consumers. The cross-price elasticity between high-sugar and reformulated lower-sugar products drove manufacturers to substitute rather than just price up (Scarborough et al., 2020). The tax worked through supply-side reformulation as well as demand-side behavior change.

Minimum Wage Debate

The minimum wage debate is partly an elasticity debate about the labor market. If labor demand is inelastic — employers need workers regardless of their wage — then raising the minimum wage increases worker income with minimal job losses. If labor demand is elastic, the job losses from wage increases are substantial.

Empirical research on this question has found smaller job effects from moderate minimum wage increases than classical theory predicted (Card & Krueger, 1994; Cengiz et al., 2019), particularly in labor markets with monopsony power where employers have pricing power over wages. This finding has substantially changed the policy debate.

Common Misunderstandings About Elasticity

"Luxury goods are always elastic": This conflates luxury with elasticity. True luxury goods — Hermes bags, Rolex watches, Formula 1 racing tickets — can exhibit Veblen behavior, where higher prices actually increase desirability by signaling exclusivity. A Rolex at half-price might actually sell fewer units because the status signal is compromised. Thorstein Veblen first described this phenomenon in The Theory of the Leisure Class (1899), noting that for certain conspicuous consumption goods, price is itself part of the product's value proposition.

"Inelastic means customers are captive forever": Inelasticity is typically a short-run or medium-run phenomenon. Over long periods, consumers adapt, new substitutes enter the market, and regulatory action may change the pricing environment. Pharmaceutical companies that exploit inelastic demand for patent-protected drugs face generic competition when patents expire — often triggering 80-90% price reductions as the market transitions to elastic conditions.

"Price elasticity is fixed": Elasticity changes with income levels, competitor activity, consumer awareness, and time. A product's elasticity in a recession differs from its elasticity in an expansion. Measuring it once and assuming permanence is a common mistake.

"Elasticity is purely an academic concept": Every major e-commerce and platform company runs continuous A/B pricing tests to measure demand elasticity in real-time. Amazon, Uber, Airbnb, and others adjust prices algorithmically based on real-time elasticity estimates, measured through randomized pricing experiments across millions of transactions. The concept is entirely operational.

Conclusion

Price elasticity is one of those economic concepts that sounds abstract until you see it in your own purchasing behavior. The reason you do not price-shop much on prescription medications but spend an hour comparing airline tickets is elasticity. The reason pharmaceutical companies, utilities, and addictive product companies can raise prices repeatedly without proportional demand loss is elasticity. The reason airlines and hotels change prices minute by minute is an attempt to price at each customer's individual elasticity.

For anyone in business, pricing is one of the most direct levers on profitability — and elasticity is the theory that makes pricing decisions systematic rather than intuitive. Understanding whether your product is elastic or inelastic, and why, is foundational to knowing how to price it, how to segment your customer base, and how to respond to competitive pressure.

For policymakers, elasticity is the underlying logic of tax design, minimum wage calculations, and market regulation. Getting it right requires empirical measurement, not assumption.

The formula is simple. The implications run through almost every major business decision and economic policy.

References

  • Marshall, A. (1890). Principles of Economics. Macmillan.
  • Tellis, G. J. (1988). The price elasticity of selective demand: A meta-analysis of econometric models of sales. Journal of Marketing Research, 25(4), 331-341. https://doi.org/10.1177/002224378802500401
  • Chaloupka, F. J., & Warner, K. E. (2000). The economics of smoking. In A. J. Culyer & J. P. Newhouse (Eds.), Handbook of Health Economics. Elsevier. https://doi.org/10.1016/S1574-0064(00)80042-6
  • Hughes, J. E., Knittel, C. R., & Sperling, D. (2008). Evidence of a shift in the short-run price elasticity of gasoline demand. Energy Journal, 29(1), 113-134. https://doi.org/10.5547/ISSN0195-6574-EJ-Vol29-No1-5
  • Goldman, D. P., et al. (2004). Pharmacy benefits and the use of drugs by the chronically ill. JAMA, 291(19), 2344-2350. https://doi.org/10.1001/jama.291.19.2344
  • Andreyeva, T., Long, M. W., & Brownell, K. D. (2010). The impact of food prices on consumption: a systematic review of research on the price elasticity of demand for food. American Journal of Public Health, 100(2), 216-222. https://doi.org/10.2105/AJPH.2008.151415
  • Gillen, D., Morrison, W. G., & Stewart, C. (2003). Air travel demand elasticities: concepts, issues and measurement. Department of Finance Canada Working Paper.
  • Herkert, D., et al. (2019). Cost-related insulin underuse among patients with diabetes. JAMA Internal Medicine, 179(1), 112-114. https://doi.org/10.1001/jamainternmed.2018.5008
  • Motta, M. (2004). Competition Policy: Theory and Practice. Cambridge University Press.
  • Smith, B. C., Leimkuhler, J. F., & Darrow, R. M. (1992). Yield management at American Airlines. Interfaces, 22(1), 8-31. https://doi.org/10.1287/inte.22.1.8
  • Card, D., & Krueger, A. B. (1994). Minimum wages and employment: a case study of the fast-food industry in New Jersey and Pennsylvania. American Economic Review, 84(4), 772-793.
  • Cengiz, D., Dube, A., Lindner, A., & Zipperer, B. (2019). The effect of minimum wages on low-wage jobs. Quarterly Journal of Economics, 134(3), 1405-1454. https://doi.org/10.1093/qje/qjz014
  • Scarborough, P., et al. (2020). Impact of the announcement and implementation of the UK Soft Drinks Industry Levy on sugar content, price, product size and number of available soft drinks in the UK. BMJ Open, 10(2). https://doi.org/10.1136/bmjopen-2019-029874
  • Veblen, T. (1899). The Theory of the Leisure Class. Macmillan.
  • Bain & Company. (2022). Bain Luxury Study 2022 Spring Update. Bain & Company.

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price elasticity economics demand pricing strategy microeconomics business strategy

Frequently Asked Questions

What is price elasticity of demand?

Price elasticity of demand (PED) measures how much the quantity demanded of a product changes in response to a price change. It is calculated as the percentage change in quantity demanded divided by the percentage change in price. An elasticity greater than 1 (in absolute value) means demand is elastic -- a price increase causes a proportionally larger drop in demand. Less than 1 means demand is inelastic -- quantity demanded is relatively insensitive to price changes.

What are examples of inelastic demand?

Gasoline, prescription medications, cigarettes, and utilities are classic examples of inelastic demand. Consumers buy similar quantities even when prices rise because these products are necessities with few substitutes. Studies have estimated gasoline's price elasticity at around -0.2 to -0.4, meaning a 10% price increase only reduces demand by 2-4%. Insulin has near-zero elasticity for diabetics who have no substitute.

What are examples of elastic demand?

Luxury goods, restaurant meals, airline tickets (economy class), and brand-name consumer electronics tend to have elastic demand. When prices rise significantly, consumers substitute with alternatives, delay purchases, or go without. Air travel price elasticity is typically estimated between -0.8 and -1.5, meaning demand is roughly proportional to price changes. Specific brand products within a category (one brand of ketchup vs another) often have high elasticity because substitutes are readily available.

What is cross-price elasticity of demand?

Cross-price elasticity measures how demand for one product changes when the price of a different product changes. Positive cross-price elasticity indicates substitutes: if the price of butter rises and demand for margarine increases, they are substitutes. Negative cross-price elasticity indicates complements: if the price of printers falls and demand for ink cartridges rises, they are complements. This helps businesses understand competitive dynamics and pricing strategy.

How do businesses use price elasticity?

Businesses use elasticity estimates to set optimal prices and predict the revenue impact of price changes. For inelastic products, raising prices increases total revenue because the drop in demand is smaller than the price increase. For elastic products, lowering prices can increase total revenue by attracting proportionally more buyers. Airlines and hotels use dynamic pricing algorithms that continually adjust prices based on real-time elasticity signals. Retailers use A/B pricing tests to directly measure elasticity for specific products.

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