Price Elasticity of Demand Calculator
Enter your before-and-after values to calculate price elasticity using the midpoint method.
What is price elasticity?
Price elasticity of demand measures how much quantity demanded changes when price changes. In simple terms, it tells you whether customers are very sensitive to price (elastic demand) or not very sensitive (inelastic demand).
Businesses use this metric to make better pricing decisions, forecast sales, and estimate how total revenue may change after a price increase or discount.
How do you calculate price elasticity?
The standard and most reliable way is the midpoint formula:
Elasticity (Ed) = [ (Q2 - Q1) / ((Q2 + Q1) / 2) ] ÷ [ (P2 - P1) / ((P2 + P1) / 2) ]
Where:
- Q1 = initial quantity demanded
- Q2 = new quantity demanded
- P1 = initial price
- P2 = new price
Why the midpoint formula is preferred
The midpoint method avoids bias from choosing one starting point. If you move from $10 to $12 or from $12 to $10, you get the same elasticity magnitude with midpoint calculations.
Step-by-step process
- Find the change in quantity: Q2 - Q1.
- Find the average quantity: (Q1 + Q2) / 2.
- Compute percentage quantity change: (Q2 - Q1) / average quantity.
- Find the change in price: P2 - P1.
- Find the average price: (P1 + P2) / 2.
- Compute percentage price change: (P2 - P1) / average price.
- Divide percentage quantity change by percentage price change.
- Use the absolute value to classify elasticity (elastic, inelastic, or unit elastic).
Example calculation
Suppose a product price rises from $20 to $24, and quantity demanded falls from 500 units to 420 units.
- % change in quantity = (420 - 500) / ((420 + 500) / 2) = -80 / 460 = -0.1739
- % change in price = (24 - 20) / ((24 + 20) / 2) = 4 / 22 = 0.1818
- Elasticity = -0.1739 / 0.1818 = -0.96
Absolute elasticity is 0.96, which is very close to unit elastic.
How to interpret the number
- |Ed| > 1: Elastic demand (customers respond strongly to price changes)
- |Ed| = 1: Unit elastic demand
- |Ed| < 1: Inelastic demand (customers respond weakly to price changes)
Most normal goods have a negative sign because price and quantity demanded usually move in opposite directions. Analysts often focus on the absolute value for classification.
Why this matters for revenue
If demand is elastic (> 1)
A price increase tends to reduce total revenue, while a price decrease can increase total revenue.
If demand is inelastic (< 1)
A price increase tends to increase total revenue, while a price decrease can reduce total revenue.
If demand is unit elastic (= 1)
Price changes tend to leave total revenue roughly unchanged.
Common mistakes to avoid
- Using raw changes instead of percentage changes.
- Ignoring the midpoint and using inconsistent bases.
- Confusing elasticity of demand with elasticity of supply.
- Treating one estimate as universal across all price ranges and seasons.
- Not accounting for competitors, substitutes, and promotions.
Quick practical tips
- Estimate elasticity for each product category, not just once for your whole business.
- Recalculate periodically as customer behavior changes over time.
- Pair elasticity analysis with margin and cost data before changing prices.
- Use controlled tests when possible (A/B pricing by segment or region).
Bottom line
To calculate price elasticity, compute the percentage change in quantity demanded, divide it by the percentage change in price, and use the midpoint formula for accuracy. Once you have the value, classify it and use it to guide smarter pricing and revenue strategy decisions.