Price Elasticity of Demand Calculator
Calculate price elasticity of demand or supply, and determine whether a product is elastic or inelastic. Understand how price changes affect revenue.
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Price Elasticity Guide
What do I need to know about Price Elasticity of Demand Formula?
PED = % change in quantity demanded ÷ % change in price. PED values: PED > 1 (elastic) — demand is sensitive to price; a 10% price rise causes >10% fall in quantity. PED < 1 (inelastic) — demand is insensitive; a 10% price rise causes <10% fall in quantity. PED = 1 (unit elastic) — percentage changes are equal. PED = 0 (perfectly inelastic) — quantity unchanged regardless of price (insulin, life-saving drugs). PED = ∞ (perfectly elastic) — consumers buy any quantity at one price but zero at any price above their maximum willingness to pay, a purely theoretical extreme rarely seen in practice.
What's the difference between Elastic and Inelastic Goods?
Inelastic demand (PED < 1) tends to apply to: necessities (food staples, medicine, utilities), goods with few substitutes, highly addictive products, goods that represent a small share of income. Elastic demand (PED > 1): luxury goods, goods with many close substitutes, non-necessities. Examples: petrol (inelastic — approximately -0.3), butter (elastic — approximately -0.8, since margarine is a substitute), foreign holidays (elastic — approximately -2.0), insulin for diabetics (nearly perfectly inelastic in the short term, since patients cannot simply stop taking essential medication regardless of price).
What's the key thing to understand about Elasticity and Total Revenue?
The critical business application: if demand is elastic (PED > 1), raising price reduces total revenue (the percentage fall in quantity exceeds the percentage rise in price). If demand is inelastic (PED < 1), raising price increases total revenue (the percentage rise in price exceeds the percentage fall in quantity). At unit elasticity (PED = 1), total revenue is maximised — a price change leaves revenue unchanged. This is why supermarkets use promotions selectively: elastic products get price cuts to boost volume and total revenue, while inelastic products are rarely discounted since a lower price would simply reduce revenue with little extra volume gained.
What's the key thing to understand about Cross-Price Elasticity and Business Strategy?
XED = % change in demand for good A ÷ % change in price of good B. Positive XED: goods are substitutes (butter and margarine). A price rise in B increases demand for A — firms try to differentiate to reduce XED between their product and competitors. Negative XED: goods are complements (printers and ink cartridges). A price rise in printers reduces demand for ink. This is why printer manufacturers sell printers cheaply and earn margins on cartridges — the negative XED means printer price strongly influences cartridge sales — a classic 'razor and blades' pricing strategy.
What Elastic and Inelastic Demand Actually Mean for Pricing Decisions
Price elasticity of demand measures how much the quantity demanded of a good changes in response to a price change, calculated as the percentage change in quantity demanded divided by the percentage change in price. When the resulting figure (ignoring sign) is greater than 1, demand is elastic — quantity demanded changes proportionally more than price, meaning a price increase will tend to reduce total revenue because the drop in units sold outweighs the higher price per unit. When it's less than 1, demand is inelastic — quantity barely responds to price, so raising price tends to increase total revenue since the modest drop in units sold is outweighed by the higher per-unit price. Goods with close substitutes, discretionary purchases, and luxury items tend toward elastic demand; necessities, addictive goods, and products with few substitutes tend toward inelastic demand.
Why Elasticity Isn't Fixed — It Changes With Price Level and Time Horizon
A single product doesn't have one fixed elasticity value across its entire price range; elasticity typically varies at different points on the demand curve, often becoming more elastic at higher price points as a product moves from being seen as reasonably priced to overpriced relative to alternatives. Elasticity also tends to differ between the short run and long run for the same product: in the short run, consumers may have no immediate substitute and keep buying despite a price rise (relatively inelastic), but given time to adjust — switching suppliers, changing habits, or finding alternatives — the same price change can produce a much larger quantity response, making long-run elasticity higher than short-run elasticity for many goods, which is an important caveat when using a single elasticity figure to forecast revenue impact.
Income Elasticity and Why It Matters for Different Product Categories
Price elasticity measures how demand responds to a change in price, but income elasticity measures something related and equally useful: how demand for a good changes as consumers' income rises or falls. Goods with high income elasticity, often called luxury or discretionary goods, see demand rise disproportionately as incomes grow; restaurant dining, travel, and premium brands typically fall into this category, meaning a given percentage increase in income produces an even larger percentage increase in spending on them. Goods with low or negative income elasticity, sometimes called necessities or inferior goods, see demand grow much more slowly than income, or even fall as income rises, because consumers substitute toward higher-quality alternatives once they can afford to; cheap, filler food staples are a commonly cited example of a good people buy less of, not more, as their income increases. For a business setting prices or planning inventory, understanding whether a product behaves as a luxury or a necessity helps predict how demand will shift through an economic upswing or downturn, independently of anything the business does with its own pricing, since income elasticity describes a response to the customer's financial circumstances rather than to the price itself.
Worked Example: Calculating Elasticity and Its Revenue Effect
A café raises the price of a sandwich from £4.00 to £4.40 (a 10% increase) and daily sales fall from 200 to 176 (a 12% decrease). Using the percentage-change method, price elasticity of demand = −%ΔQuantity / %ΔPrice = −12% / 10% = −1.2. Because the absolute value (1.2) is greater than 1, demand is elastic at this price point: the proportional drop in quantity outweighs the proportional rise in price. Checking the revenue effect confirms it: old revenue was 200 × £4.00 = £800/day; new revenue is 176 × £4.40 = £774.40/day — revenue fell even though the price went up, which is the signature of elastic demand. Had elasticity instead been −0.6 (inelastic, quantity falling proportionally less than price rises), revenue would have increased. This is why "raise the price to make more money" only works below a certain point on the demand curve for any given product — above it, the quantity lost costs more than the extra margin gained.
Typical Elasticity Ranges by Product Category
| Elasticity Range | Demand Classification | Typical Example Categories |
|---|---|---|
| Greater than 1 in magnitude (e.g. −2.5) | Elastic | Restaurant meals out, branded goods with many close substitutes, discretionary travel |
| Around −1 (unit elastic) | Unit elastic | Revenue roughly unchanged by small price moves |
| Less than 1 in magnitude (e.g. −0.3) | Inelastic | Petrol/fuel in the short run, prescription medicine, basic utilities |
| Near zero | Perfectly/highly inelastic | Insulin for someone who needs it, salt historically |
These categories are illustrative tendencies, not fixed laws — elasticity for the same product can shift with income levels, available substitutes, and especially time horizon (demand for petrol is far more elastic over 3 years, once people can change cars or commuting habits, than over 3 weeks).
Frequently Asked Questions
Why is elasticity usually expressed as a negative number but discussed as a positive one?
Price and quantity demanded normally move in opposite directions, so the raw calculation is negative for almost all ordinary goods. Economists often refer to the absolute value (e.g. "elasticity of 1.2") for convenience, but the sign is mathematically there and matters for rare exceptions like Veblen goods.
Can a product be elastic at one price and inelastic at another?
Yes — elasticity is a local measure that typically changes along the demand curve. A product can be relatively inelastic at a low price point (little room to cut further) and become highly elastic once the price crosses a psychological or budget threshold for most buyers.
How is cross-price elasticity different from regular price elasticity?
Regular (own-price) elasticity measures how a product's own price change affects demand for that same product. Cross-price elasticity measures how a change in the price of one good affects demand for a different good — positive for substitutes (e.g. butter and margarine) and negative for complements (e.g. printers and ink).