A good is elastic when consumers significantly change how much they buy in response to a price change. Specifically, if a 10% price increase causes more than a 10% drop in quantity demanded, that good is elastic. The concept helps explain why some products can absorb price hikes without losing many buyers, while others see sales plummet the moment prices tick upward.
The Elasticity Coefficient Explained
Elasticity is measured with a simple ratio: the percentage change in quantity demanded divided by the percentage change in price. The result is called the elasticity coefficient. If it’s greater than 1, the good is elastic. If it’s less than 1, the good is inelastic. A coefficient of exactly 1 is called unit elastic, meaning demand changes at the same rate as price.
Here’s a quick example. Say a store raises the price of a product from $10 to $12, a 20% increase. If sales drop from 100 units to 80 units, that’s a 20% decrease. The elasticity coefficient is 20% ÷ 20% = 1.0, right at the boundary. But if sales dropped from 100 to 70 units (a 30% decrease), the coefficient would be 1.5, making it elastic. Consumers reacted to the price change more than proportionally.
What Makes a Good Elastic
Several factors push a good toward being elastic, and they all come down to how easy it is for consumers to walk away.
- Availability of substitutes. This is the single biggest factor. A product with many alternatives tends to be highly elastic because consumers can simply switch. A Big Mac is elastic because you can eat a Whopper, a burrito, or a sandwich instead. Gasoline as a category has fewer substitutes for most drivers, though individual gas station brands are very elastic since you can just drive to the next station.
- Necessity vs. luxury. Necessities tend to be inelastic because people buy them regardless of price. When the price of bread or insulin rises, consumption barely budges. Luxuries and nonessential goods like jewelry, dining out, and electronics are more elastic because people can simply go without them.
- Share of your budget. The more a product costs relative to your income, the more sensitive you are to its price. A 20% increase on a pack of gum barely registers, but a 20% increase on rent changes behavior dramatically. Research in the American Journal of Public Health confirms this pattern: the larger the budget share of a good, the higher its price elasticity.
- Time horizon. Demand often becomes more elastic over time. In the short run, you might keep buying gas at a higher price because you need to get to work. Over months or years, though, you might carpool, buy a more efficient car, or move closer to your job.
Elastic Goods in Practice
Soft drinks are a good real-world example. A study measuring price sensitivity in Bangladesh found that a 10% price increase on soft drinks led to roughly a 10.6% drop in consumption, giving them an elasticity coefficient of about 1.06. Tea purchased at shops or cafes was even more elastic at 1.10, meaning a 10% price bump cut demand by 11%. But tea brewed at home had a coefficient of 0.88, making it inelastic. The difference makes sense: buying tea at a café is a convenience you can skip, while making tea at home is more of a daily habit with fewer easy substitutes.
Nonessential consumer goods like electronics, fashion, and impulse purchases generally fall on the elastic side. When prices rise on items people don’t strictly need, they delay purchases, buy cheaper alternatives, or skip buying altogether. Essentials like basic groceries, utilities, and medical care sit on the inelastic end because cutting back isn’t really an option.
Why Elasticity Matters for Prices You Pay
Elasticity directly shapes how businesses set prices and how those prices affect their revenue. When demand for a product is elastic, raising the price actually lowers total revenue. The drop in sales more than offsets the higher price per unit. This is why competitive restaurants rarely raise prices aggressively. They know diners will simply eat somewhere else.
The reverse is also true. If a company sells a product with elastic demand, lowering the price can boost total revenue because the increase in sales volume outweighs the smaller profit per item. This is the logic behind sales, discounts, and promotional pricing on nonessential goods. Companies selling elastic products are cautious about price increases because even small changes can produce large drops in demand and total revenue.
For inelastic goods, the math flips. A company selling something people need, with few alternatives, can raise prices and watch revenue climb because customers keep buying at nearly the same rate. This is why prescription drug prices and utility bills can rise without a proportional loss in customers.
Income Levels Change Elasticity
The same product can be elastic in one context and inelastic in another, depending on who’s buying. Research across countries shows that higher-income nations tend to have lower price elasticity for food products than lower-income nations. When food takes up a small fraction of your household budget, a price increase doesn’t force much of a change. But when food already consumes a large share of your income, the same price increase might force you to cut back or switch to cheaper alternatives.
This is why economists sometimes describe luxuries and necessities in terms of elasticity rather than making subjective judgments about what people “need.” A luxury, in economic terms, is simply a good where spending increases faster than income rises. A necessity is one where spending stays relatively flat no matter what happens to income or price. People’s own perceptions of what counts as a luxury closely track the economic concept of price elasticity, suggesting the formal definition matches everyday intuition pretty well.