Price Elasticity of Demand (PED) Category Calculator
Enter the old and new price/quantity values. This calculator uses the midpoint method to compute PED and assign a demand category.
| |PED| Range | Category |
|---|---|
| 0 | Perfectly Inelastic |
| 0 < |PED| < 1 | Inelastic |
| |PED| = 1 | Unitary Elastic |
| |PED| > 1 | Elastic |
| |PED| → ∞ | Perfectly Elastic (theoretical) |
What this PED category calculator does
The Price Elasticity of Demand (PED) measures how sensitive buyers are to a price change. In plain language: if price moves up or down, how strongly does quantity demanded respond?
This tool calculates PED using two points in time (before and after a change), then places the result into a category like inelastic or elastic. That category helps with pricing decisions, revenue planning, and demand forecasting.
Formula used in this calculator
Midpoint method (recommended)
Instead of using only the initial value as a base, the midpoint method uses the average of old and new values. This avoids getting different answers depending on direction of change.
- % Change in Quantity = (Q2 - Q1) / ((Q1 + Q2) / 2) × 100
- % Change in Price = (P2 - P1) / ((P1 + P2) / 2) × 100
- PED = (% Change in Quantity) / (% Change in Price)
Since demand usually falls when price rises, PED is often negative. For category labeling, economists commonly use absolute value (|PED|).
How to interpret PED categories
1) Perfectly Inelastic (|PED| = 0)
Quantity demanded does not change at all when price changes. This is rare in real markets, but some necessities can behave close to this.
2) Inelastic (0 < |PED| < 1)
Quantity changes by a smaller percentage than price. Customers are relatively less sensitive to price changes.
3) Unitary Elastic (|PED| = 1)
Quantity changes by the same percentage as price. Revenue impact can be balanced at this point.
4) Elastic (|PED| > 1)
Quantity changes by a larger percentage than price. Customers are price-sensitive, and pricing moves can strongly affect sales volume.
5) Perfectly Elastic (|PED| approaches infinity)
Theoretical case where tiny price changes trigger extremely large quantity changes. Useful conceptually, uncommon in pure form.
Why PED category matters for pricing
- Revenue strategy: With inelastic demand, moderate price increases may raise total revenue.
- Promotion planning: With elastic demand, discounts can drive larger volume gains.
- Market positioning: PED reveals whether buyers see close substitutes.
- Risk management: High elasticity warns that pricing errors can quickly reduce sales.
Worked example
Suppose price rises from 10 to 12 while quantity demanded falls from 500 to 420.
- %ΔQ = (420 − 500) / 460 × 100 = −17.39%
- %ΔP = (12 − 10) / 11 × 100 = +18.18%
- PED = −17.39 / 18.18 = −0.96
The absolute value is 0.96, so demand is approximately inelastic to near-unitary, depending on rounding tolerance.
Common mistakes to avoid
- Mixing units (for example, price in dollars but quantity in cases one month and units the next month).
- Using raw differences instead of percentage changes.
- Ignoring external factors like seasonality, advertising, stockouts, or competitor actions.
- Treating one observation as permanent truth—elasticity can vary by segment, time, and price band.
Final note
A PED category calculator is best used as a decision aid, not as a standalone decision maker. Combine elasticity results with margin data, customer behavior, and competitive context to make pricing choices that are both profitable and sustainable.