Price Elasticity Calculator

The price elasticity of demand calculator uses the midpoint method from OpenStax Principles of Economics 3e, section 5.1 (published December 14, 2022). Calculate both percentage changes, then divide:

• % change in quantity = (Q2 − Q1) ÷ ((Q2 + Q1) ÷ 2) × 100
• % change in price = (P2 − P1) ÷ ((P2 + P1) ÷ 2) × 100
• Price elasticity of demand = % change in quantity ÷ % change in price

Averaging the old and new values makes the midpoint method symmetric. Divide by the starting value alone and a move from $120 to $130 reads as an 8.3% rise, while the move back down reads as a 7.7% price decrease, so the same two prices give two different elasticities. The devil's in the details here. The midpoint version returns 1.47 in both directions.

Signs carry information, so the main result keeps the minus. A negative coefficient is the normal demand formula outcome. A positive one on the own-price tab is a red flag that something else moved consumers between your two periods (a competitor stock-out, a seasonal spike, a marketing push), and the change in quantity demanded can't be pinned on the change in price.

Each revenue calculation is price times quantity at one point. The scenario table projects further price changes from your new price with a constant-elasticity shortcut, % change in quantity ≈ elasticity × % change in price, which holds for small moves near the two points you entered.

The cross price elasticity tab of the calculator divides the midpoint change in the quantity of good A by the midpoint change in the price of good B. Per OpenStax section 5.4, substitutes carry a positive value and complements a negative one.

Take the example OpenStax uses in section 5.1 and calculate it by hand. A business moves a product from an initial price of $120 to a new price of $130, and the quantity demanded falls from an initial quantity of 1,800 to a new quantity of 1,600.

• % change in quantity: (1,600 − 1,800) ÷ 1,700 × 100 = −11.76%
• % change in price: (130 − 120) ÷ 125 × 100 = 8.00%
• Price elasticity of demand: −11.76 ÷ 8.00 = −1.47, elastic
• Total revenue: $216,000 before, $208,000 after, a loss of $8,000 (−3.7%)

A $10 price increase cost $8,000 of revenue because consumers left faster than the price rose. From the new $130 price, the calculator's scenario table shows a 10% cut lifting demand about 14.7% to 1,835 and revenue to $214,729, a starting estimate for the next test.

In a hypothetical cross price elasticity example, a coffee shop raises its latte price from $4.00 to $5.00 and sells 1,000 cappuccinos a week, up from 900. Quantity demanded changes 10.53% and price 22.22% at the midpoints, so the result is +0.47, which marks the two drinks as substitutes.

Arc price elasticity of demand measures one stretch of the demand curve, set by your two price points. OpenStax's own curve shows how much that matters: the stretch from $60 to $70 comes out at 0.45, inelastic, and the stretch from $120 to $130 at 1.47, elastic.

The math assumes price was the only thing that changed. A holiday week, an ad campaign or a competitor's price cut between your two periods ends up inside the coefficient. Sales data from several price changes, or a controlled experiment splitting traffic between prices, gives a cleaner reading of consumer behavior.

OpenStax section 5.3 also notes that price elasticity of demand is often lower in the short run than in the long run. Its estimates table puts gasoline at 0.35, and energy buyers react more once they can switch cars or insulate a home.

Several factors affect demand elasticity, and the elasticity of demand calculator reports their combined effect in one number:

• Substitutes: demand gets more elastic as consumers find more close alternatives.
• Necessity: the more of a necessity a product is, the less consumers react, so essential goods and necessary goods sit on the inelastic side, and luxury goods on the elastic side.
• Share of income spent: a price change on something that costs an arm and a leg gets noticed, while a slight increase on a $2 item often goes unseen.
• Time horizon: alternatives take months to find.

It also stops at revenue. A price decrease that grows revenue can still cut a business's profit once the cost of each extra sale is counted, so pair the result with your margin. For a business with thousands of SKUs, price optimization tools estimate elasticity per product from transaction data, conjoint analysis tools estimate willingness to pay before a price ever changes, and pricing intelligence tracks the competitor prices that move your market.

Price elasticity of demand measures how the demand for a good or service responds to a change in its own price. A price elasticity of demand of −2 means a 1% price increase cuts sales by about 2%.

Inelastic. At a price elasticity of demand of 0.5, raise prices 10% and quantity falls about 5%, so total revenue goes up about 4.5%. Consumers of an inelastic product take the increase in stride. Cigarettes are the textbook example of an inelastic good. OpenStax cites an estimate of 0.3, where a 10% price rise cuts the quantity adults smoke by about 3%.

Elastic. A price elasticity of demand of 1.25 sits above 1, so a 4% price rise cuts quantity by about 5% and revenue falls. Perfectly elastic demand is the limit case, where any price rise drops quantity to zero, and luxury goods with many substitutes sit toward that end.

A price elasticity of demand of 1.2 means each 1% change in price moves quantity demanded about 1.2% the other way. That's close to unitary elastic. At exactly 1, demand is unit elastic and revenue stays equal as price moves. A 10% rise at 1.2 loses about 12% of volume and 3.2% of revenue. At 2.5 the same rise loses about 25% of volume and 17.5% of revenue.

Divide the percentage change in quantity demanded of good A by the percentage change in the price of good B, using the midpoint method in both halves of the calculation. A positive result marks substitutes and a negative one marks complements (pricier printers sell fewer ink cartridges), and a value near zero means the products barely interact.

With a demand function Q = f(P), point elasticity is (dQ/dP) × (P/Q), the slope of the demand function times P/Q. For a linear demand function Q = 1,000 − 20P at P = $30, the slope is −20 and Q is 400, so elasticity is −20 × 30 ÷ 400 = −1.5. Use it to calculate elasticity at a single price. The elasticity of demand calculator above needs two observed prices. Perfectly inelastic demand has a slope of zero.

Yes. Swap in quantity supplied and the midpoint formula returns price elasticity of supply. For example, OpenStax's apartment case (rent from $650 to $700, units supplied from 10,000 to 13,000) gives 3.53, positive because price and supply move the same way.

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