Price elasticity formula

The formula for price elasticity of demand is:

$$E_d = \frac{\% \Delta Q_d}{\% \Delta P}$$

Where:

• $E_d$ is the price elasticity of demand.
• $\% \Delta Q_d$ is the percentage change in quantity demanded.
• $\% \Delta P$ is the percentage change in price.

This can also be expressed as:

$$E_d = \frac{\frac{Q_2 - Q_1}{Q_1}}{\frac{P_2 - P_1}{P_1}}$$

Or, using calculus for infinitesimal changes:

$$E_d = \frac{dP}{dQ} \times \frac{P}{Q}$$