Free price elasticity of demand calculator
Measure how price-sensitive your customers are in two seconds. Enter the price and quantity before a price change and after it — the calculator returns the price elasticity of demand using the midpoint method, the percentage change in quantity and price, and whether demand is elastic or inelastic — updated live, as you type.
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Estimates only, based on the two price/quantity points you enter. Not financial advice.
Results are estimates. Consult a professional.
What is price elasticity of demand?
Price elasticity of demand (PED) measures how much the quantity demanded of a good changes when its price changes. It answers the single question every business and economist cares about: if I raise the price by 10%, how many customers walk away? A good is elastic when buyers are sensitive to price — a small price rise sends demand falling sharply — and inelastic when they are not, so demand barely moves. This price elasticity of demand calculator returns the number the moment you enter two prices and the two quantities sold at those prices.
Because demand normally falls as price rises, the raw ratio is negative. By convention we report its absolute value and read the size: the further |PED| sits above 1, the more elastic the good; the closer it sits to 0, the more inelastic. The calculator above shows the negative percentage changes behind the figure so the direction is never hidden.
The price elasticity of demand formula
At its simplest, price elasticity of demand is the percentage change in quantity demanded divided by the percentage change in price:
The catch is how you compute each percentage change. The naive approach divides the change by the starting value, which gives a different answer depending on whether the price rose or fell between the same two points. To fix that, this calculator uses the midpoint (arc) method, which divides by the average of the two values instead. The next two sections show the midpoint formula in full and contrast it with the point method.
How to calculate price elasticity of demand with the midpoint method
The midpoint method — also called the arc elasticity method — uses the average of the two prices and the average of the two quantities as the base of each percentage change. This is the formula taught in most introductory microeconomics courses and the one this calculator applies.
- Find the change in quantity and divide it by the average of the two quantities to get the percentage change in quantity demanded.
- Find the change in price and divide it by the average of the two prices to get the percentage change in price.
- Divide the quantity change by the price change and take the absolute value. That number is your price elasticity of demand.
Midpoint method vs. point method
There are two common ways to compute the percentage changes, and they can give noticeably different answers over a large price move. Knowing which one a calculator uses matters when you compare results.
| Point (basic) method | Midpoint (arc) method | |
|---|---|---|
| Base of % change | Starting value (P1, Q1) | Average of the two values |
| Symmetric? | No — rise and fall differ | Yes — same either direction |
| Best for | A tiny change at one point | A measurable change between two points |
| Used by this calculator | — | Yes |
The point method is fine for very small changes; the midpoint method is the standard for two discrete observations.
A third approach, point elasticity, uses calculus on a known demand function — PED = (dQ/dP) × (P/Q) — and is used when you have the demand equation itself rather than two observed points. For the two-point case that businesses actually face, the midpoint method is the right tool, which is why it powers the calculator above.
A worked example using the price elasticity of demand calculator
A café currently sells 1,000 cups a week at $2.50. To lift revenue it raises the price to $3.00 and the next week sells 800 cups. Is coffee elastic for these customers? Here is how the calculator works it out — quantity change first, then price change, then the ratio.
Step 1 — Find the percentage change in quantity
Quantity fell from 1,000 to 800 cups. The midpoint base is the average, (1,000 + 800) ÷ 2 = 900. So the percentage change in quantity is (800 − 1,000) ÷ 900 = −22.2%.
Step 2 — Find the percentage change in price
Price rose from $2.50 to $3.00. The midpoint base is (2.50 + 3.00) ÷ 2 = 2.75. So the percentage change in price is (3.00 − 2.50) ÷ 2.75 = +18.2%.
Step 3 — Divide to get the elasticity
| Input | Value |
|---|---|
| % change in quantity | −22.2% |
| % change in price | +18.2% |
| PED = 22.2% ÷ 18.2% | 1.22 |
Take the absolute value of −22.2% ÷ 18.2% to get |PED| = 1.22.
Elastic vs. inelastic: how to read your PED value
The size of |PED| sorts every good into one of five bands. The calculator labels your result automatically, but here is the full scale so you can place any value in context.
| |PED| value | Classification | What it means |
|---|---|---|
| 0 | Perfectly inelastic | Quantity never changes, whatever the price (e.g. a life-saving drug). |
| Between 0 and 1 | Inelastic | Demand changes less than price — buyers are insensitive. |
| Exactly 1 | Unit elastic | Demand changes in exact proportion to price. |
| Greater than 1 | Elastic | Demand changes more than price — buyers are sensitive. |
| ∞ (infinity) | Perfectly elastic | Any price rise drops demand to zero (a perfect-substitute market). |
Classification bands for the absolute value of price elasticity of demand.
Price elasticity and total revenue
The most valuable use of price elasticity is pricing. Total revenue is price times quantity, and elasticity tells you which way revenue moves when you change the price — because a price change pulls those two terms in opposite directions.
- Elastic (|PED| > 1): raising the price lowers total revenue, because quantity falls by a larger percentage than price rises. To grow revenue, cut the price.
- Inelastic (|PED| < 1): raising the price raises total revenue, because quantity barely falls. This is why fuel, tobacco, and utilities can pass on price increases.
- Unit elastic (|PED| = 1): total revenue is at its maximum and a small price change leaves it unchanged.
What determines price elasticity of demand?
Why is salt inelastic while a particular brand of cereal is elastic? Five factors decide how price-sensitive demand for any good will be.
- Availability of substitutes. The more close substitutes a good has, the more elastic it is — buyers switch the moment the price rises. Unique goods with no substitute are inelastic.
- Necessity vs. luxury. Necessities (insulin, electricity, basic food) are inelastic because people buy them regardless of price; luxuries are elastic because they can be skipped.
- Share of income. Goods that take a large slice of the budget (a car, a holiday) are elastic; cheap items (a box of matches) are inelastic because the price barely registers.
- Time horizon. Demand is more elastic over the long run — given time, buyers find alternatives, change habits, or buy efficient appliances. In the short run it is more inelastic.
- Breadth of the market. A narrowly defined good (one brand of soda) is more elastic than a broadly defined one (all soft drinks), because the narrow good has more substitutes.
Examples of elastic and inelastic goods
Real-world goods cluster predictably along the elasticity scale. These are illustrative ranges, not precise constants — elasticity shifts with the market, the time frame, and how narrowly the good is defined.
| Good | Typical demand | Why |
|---|---|---|
| Insulin, salt, tap water | Highly inelastic | Necessities with no substitute. |
| Gasoline, electricity | Inelastic (short run) | Hard to avoid until alternatives exist. |
| Restaurant meals, airline seats | Elastic | Easy to delay or substitute. |
| A single brand of soda | Highly elastic | Many near-identical substitutes. |
Indicative classifications; actual elasticity varies by market and time horizon.
Limitations and common mistakes
- It assumes nothing else changed. PED isolates price, but real demand also moves with income, tastes, and competitors' prices. If those shifted between your two observations, the figure is contaminated.
- It is a snapshot, not a curve. Elasticity varies along a demand curve, so a value measured between $2 and $3 need not hold between $8 and $9.
- Drop the minus sign carefully. The raw ratio is negative; report the absolute value, but remember demand and price always move in opposite directions.
- Don't confuse it with cross or income elasticity. Price elasticity of demand measures response to a good's own price — not the price of a related good, nor a change in income.
Method and sources
This calculator computes price elasticity of demand with the midpoint (arc) elasticity method, the standard taught in introductory microeconomics. It divides the percentage change in quantity demanded by the percentage change in price, using the average of each pair of values as the base, and reports the absolute value with its classification band.
Federal Reserve Bank of St. Louis — Price Elasticity of Demand, Explained.Frequently asked questions about the free price elasticity of demand calculator
About this price elasticity of demand calculator
This price elasticity of demand calculator runs entirely in your browser. Every figure you enter stays on your device — nothing is sent to a server, logged, or shared. It applies the midpoint (arc) method, dividing the percentage change in quantity demanded by the percentage change in price over the average of each pair, reports the absolute value, and classifies the result as elastic, inelastic, or unit elastic — updating instantly as you type.
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