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ECONOMICS • MICROECONOMICS

Price Elasticity of Demand

Move along a linear demand curve and see how price elasticity changes from inelastic to unit elastic to elastic, together with revenue.

● ELASTICITY MAPPrice sensitivity
Quantity demanded
Elasticity |E|
Classification
Revenue

Reasoning inspector

live model state
Point elasticity—
Classification—
Quantity—
Revenue—
Revenue-max price—
Maximum revenue—

Elasticity is a point on the demand curve

The same linear demand curve can be inelastic at low prices and elastic at high prices. Move the price and compare the percentage response of quantity with the change in total revenue.

LEARN WITH THE SIMULATION

Understand Price Elasticity of Demand by experimenting.

START HERE

Price elasticity of demand measures how strongly quantity demanded responds to price in percentage terms. Even on one straight demand curve, elasticity is not constant: the same slope can be inelastic near the low-price high-quantity end, approximately unit elastic near the midpoint, and elastic near the high-price low-quantity end.

BUILD THE IDEA

What you should understand first

  • Compute point elasticity on a linear demand curve using the local slope and the current price-to-quantity ratio.
  • Distinguish the geometric slope of a demand curve from the unit-free elasticity measured at a particular point.
  • Connect elastic, unit-elastic and inelastic regions with the direction in which total revenue changes.
  • Locate the revenue-maximizing midpoint of a linear demand curve.

TRY IT YOURSELF

Why can one straight demand curve contain both elastic and inelastic regions?

  1. Keep the demand intercept and slope fixed and start with a low price.
  2. Raise the price gradually while watching quantity, elasticity and revenue.
  3. Find the region where elasticity is close to one and compare revenue with nearby prices.
  4. Continue toward the choke price and observe how a smaller quantity makes the price-to-quantity ratio larger.
Read the visual:

The slope stays fixed, but elasticity rises as price increases and quantity falls. For a linear demand curve, total revenue is maximized near unit elasticity; revenue moves in opposite directions on the elastic and inelastic sides.

WHY IT WORKS 01

Slope has units; elasticity does not

The slope of a demand curve depends on how price and quantity are measured, so changing units can change the numerical slope. Elasticity rescales the slope by P/Q, producing a unit-free measure that is more meaningful for comparing responsiveness across different prices, quantities and markets.

WHY IT WORKS 02

The revenue connection

When demand is elastic, the percentage quantity response dominates the percentage price change, so raising price lowers total revenue. When demand is inelastic, the price effect dominates and revenue rises with price. At unit elasticity the opposing percentage effects balance, which is why the midpoint of a linear demand curve maximizes revenue.

DO NOT MIX THESE UP

Common misconception

Elasticity is not the same thing as slope, and a straight demand line does not have one constant point elasticity. A large numerical elasticity does not mean demand itself is large; it means the percentage quantity response is large relative to the percentage price change at that point.

PRACTICE CHALLENGE

Can you find unit elasticity without being told the midpoint formula?

  • Choose any intercept and slope and slowly move the price until the elasticity metric is near one.
  • Record the price and quantity at that point.
  • Compare the price with half the choke price and the quantity with half the demand intercept.
Reveal the reasoning

For a linear demand curve Q = A − bP, setting bP/Q = 1 gives bP = A − bP, so P = A/(2b). That is exactly half the choke price, and the corresponding quantity is A/2. The interactive revenue maximum should line up with the same point.

MODEL BOUNDARIES

What this simulation assumes

Every simulation simplifies reality or a mathematical system. These are the assumptions and limits to keep in mind while interpreting the results.

Model assumptions

  • Demand follows the linear relationship Q equals intercept minus slope times price over the displayed range.
  • Point elasticity uses the absolute value of the local derivative multiplied by the current price-to-quantity ratio.
  • Total revenue is modeled as price times quantity demanded with no cost, capacity or strategic-pricing model.

Model limitations

  • Real demand may be nonlinear and elasticity can depend on time horizon, substitutes, income, expectations and market definition.
  • The simulation does not estimate elasticity from observed data or model supply-side profit maximization.

CONNECT IT

Where this matters

  • Pricing and revenue reasoning
  • Demand sensitivity comparisons
  • Microeconomics and market analysis
  • Interpreting consumer response to price changes

WORDS THAT MATTER

Key vocabulary

Price elasticity of demand
The magnitude of the percentage change in quantity demanded associated with a one-percent change in price at a point.
Elastic demand
A region where the magnitude of price elasticity is greater than one.
Inelastic demand
A region where the magnitude of price elasticity is less than one.
Total revenue
Price multiplied by quantity sold in this simplified demand-side model.