Unitary elasticity describes a situation where a percentage change in price produces an exactly equal percentage change in the quantity people buy. If the price of a product rises by 10%, the quantity demanded falls by 10%. The elasticity coefficient equals exactly 1, placing it at the precise boundary between elastic and inelastic.
How Unitary Elasticity Works
Economists measure how sensitive buyers (or sellers) are to price changes using a concept called price elasticity. The basic idea is a ratio: the percentage change in quantity divided by the percentage change in price. When that ratio equals 1, you have unitary elasticity. When it’s greater than 1, demand is elastic, meaning consumers are highly responsive to price shifts. When it’s less than 1, demand is inelastic, meaning consumers barely change their buying behavior.
Unitary elasticity sits right at the tipping point. A 1% increase in price causes exactly a 1% decrease in quantity demanded. A 5% price drop leads to a 5% increase in quantity demanded. The responsiveness is perfectly proportional.
Why Total Revenue Stays Flat
The most practical consequence of unitary elasticity is what happens to total revenue, which is simply price multiplied by quantity sold. When elasticity equals 1, any price change leaves total revenue unchanged. Here’s why: if you raise the price by 10%, you lose exactly 10% of your customers. The higher price per unit is perfectly offset by fewer units sold. The math works the same in reverse. Cut the price by 10%, and 10% more people buy, but each pays less. Revenue stays constant.
This makes unitary elasticity the dividing line for pricing strategy. With elastic demand (coefficient above 1), lowering prices actually increases total revenue because the surge in quantity more than compensates for the lower price. With inelastic demand (coefficient below 1), raising prices increases revenue because buyers don’t cut back enough to offset the higher price. At unitary elasticity, neither strategy gains you anything.
Total Spending From the Consumer’s Side
From the buyer’s perspective, unitary elasticity means you spend the same total amount on a product regardless of its price. If baseball tickets have a price elasticity of 1.0 and ticket prices rise, you buy fewer tickets but your total spending on baseball stays the same. Your budget allocation to that product doesn’t shift. This is a useful way to think about it practically: unitary elastic goods are ones where your wallet commitment stays constant even as the sticker price moves around.
What the Curves Look Like on a Graph
A demand curve that has unitary elasticity at every single point takes the shape of a rectangular hyperbola. This is a smooth curve that bends toward both axes but never touches either one. The defining feature is that if you pick any point on the curve and draw a rectangle from that point to the axes, the area of that rectangle (which represents total revenue) is the same no matter which point you choose. That geometric property is just another way of visualizing the constant-revenue idea.
Most real-world demand curves aren’t rectangular hyperbolas, though. A straight-line demand curve, the kind drawn in introductory economics, has unitary elasticity at only one point along its length. Near the top of the curve (high price, low quantity), demand is elastic. Near the bottom (low price, high quantity), demand is inelastic. Unitary elasticity occurs at the midpoint. This is a common source of confusion: slope and elasticity are not the same thing. A straight demand curve has a constant slope but a changing elasticity.
Supply curves with unitary elasticity look different. A supply curve with constant unitary elasticity is a straight line that passes through the origin of the graph. Any straight supply line through the origin has this property, regardless of its steepness.
How Elasticity Is Calculated
The standard formula divides the percentage change in quantity by the percentage change in price. There’s one wrinkle worth knowing: depending on whether you calculate the percentage change based on the starting value or the ending value, you can get different answers. Economists handle this with the midpoint method, which uses the average of the two quantities and the average of the two prices as the base for calculating percentages. This ensures you get the same elasticity whether you’re looking at a price increase or a price decrease between the same two points.
For example, if the price rises from $10 to $11 and quantity supplied rises from 80 to 88 units, the midpoint method calculates a 9.52% change in both quantity and price. Dividing one by the other gives an elasticity of exactly 1.0, confirming unitary elasticity in that range.
Where Unitary Elasticity Shows Up
Perfect unitary elasticity across all price ranges is more of a theoretical benchmark than something you encounter often in real markets. Most goods shift between elastic and inelastic depending on the price level, the time horizon, and whether close substitutes exist. But the concept is essential for understanding how revenue behaves, how consumers allocate spending, and where the boundary sits between products that are price-sensitive and those that aren’t. It gives you the reference point: at exactly 1, price changes are a wash.