What it means
The calculation compares two percentage changes: the change in quantity sold and the change in price that caused it. Because price and quantity normally move in opposite directions the result is negative, so most people quote the absolute value and simply say "elasticity of 1.5".
The dividing line sits at 1. Above 1 demand is elastic and a price rise reduces total revenue, while below 1 demand is inelastic and a price rise increases total revenue even though some customers leave.
What drives elasticity is mainly the availability of alternatives and the share of the customer's budget the purchase takes. Petrol and prescription medicines are inelastic because substitutes are poor and the need is immediate, while a particular brand of biscuit is elastic because a nearly identical product sits on the next shelf.
Time matters more than most managers expect. Demand is usually far more inelastic in the short run than the long run, because customers need time to find alternatives, requalify suppliers or change their habits, which is why a price rise can look successful for two quarters and painful after two years.
The same logic applies beyond price. Income elasticity measures how demand responds to customer incomes and cross elasticity measures how demand for your product responds to a competitor's price change, both of which are useful when planning through a downturn.
In practice
Real-world examples.
Example
A rail operator raises off-peak fares by 8% and sees off-peak journeys fall by 12%, giving an elasticity of about 1.5. Peak fares rise by the same 8% and journeys fall only 2%, an elasticity of 0.25, because commuters have no realistic alternative at that hour.
Example
A craft brewery raises the trade price of its flagship beer by 5% and loses 4% of volume, an elasticity of 0.8. Because demand is inelastic, revenue rises, and the brewery uses the extra margin to fund a second fermentation tank.
Example
A software vendor increases the price of its premium tier by 20% and loses 35% of upgrades, an elasticity of 1.75. The team responds by leaving the price in place but adding two features to the tier, aiming to make demand less elastic rather than reversing the increase.
Formula
Calculation
Price elasticity of demand = percentage change in quantity demanded / percentage change in price.
A gym raises its monthly membership from $50 to $55. That is a price change of $5 / $50 = 0.10, which is a 10% increase.
Membership falls from 10,000 to 8,500 people. That is a quantity change of -1,500 / 10,000 = -0.15, which is a 15% decrease.
Elasticity = -15% / 10% = -1.5, usually quoted as 1.5. Because this is above 1, demand is elastic and revenue should fall: monthly revenue before was $50 x 10,000 = $500,000, and after the rise it is $55 x 8,500 = $467,500, a drop of $32,500 per month.Case study
Seen in the real world.
This is an illustrative and clearly fictional example. Selwyn Home Goods, a homeware retailer, applied a flat 7% price increase across its entire catalogue to cover rising freight costs. Six months later total revenue was almost exactly flat, which the board initially read as a neutral outcome.
A category-level review told a different story. Elasticity in kitchen basics, where supermarkets sold near-identical items, was around 2.0 and revenue there fell by 7%, while elasticity in bespoke curtains and made-to-measure blinds was around 0.4 and revenue there rose by 5%. The flat increase had quietly moved the business away from the categories it made money in.
In the illustrative outcome, the company rolled back the increase on the elastic categories, pushed a further 6% onto the inelastic ones, and recovered the freight cost without losing volume where it mattered.
Watch out
Common mistakes.
- Applying one elasticity figure across a whole catalogue when different products and customer segments respond very differently to the same price change.
- Ignoring the minus sign convention and then arguing about whether an elasticity of -1.5 is more or less elastic than 0.8, when the comparison should use absolute values.
- Measuring elasticity from a promotional discount and assuming the same response applies to a permanent price change, even though a temporary offer pulls forward purchases people would have made anyway.
Questions
People also ask.
What counts as elastic demand?
An absolute elasticity above 1, meaning quantity moves proportionally more than price, so a price rise lowers total revenue.
Does inelastic demand mean I can raise prices indefinitely?
No, elasticity is measured over a range and it typically rises as prices climb, so a product that is inelastic at $20 may be highly elastic at $35.
Why do businesses use the midpoint method?
Because calculating percentage changes from the average of the old and new values gives the same elasticity whether the price went up or down, which avoids two different answers for the same pair of prices.
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