The PES Formula — Price Elasticity of Supply (PES) | IGCSE Economics

Exam Frequency Analysis

Past paper frequency (2018 to 2024)

This topic accounts for approximately 10% of your exam marks.

stable

Medium

Stable10%

PES definition, formula, calculation, and determinants appear on most papers; typically 4 to 6 marks paired with PED or market analysis questions.

$\text{PES} = \dfrac{\%\,\Delta\,Q_s}{\%\,\Delta\,P}$

PES is the percentage change in quantity supplied divided by the percentage change in price. Both numbers are percentages, not raw unit changes. The percentage-change formula is the same as for PED:

$\% \,\text{change} = \dfrac{\text{new value} - \text{old value}}{\text{old value}} \times 100$

PES for a normal good is positive. The supply curve slopes upward, so a price rise produces a quantity-supplied rise; both percentage changes have the same sign and the ratio is positive. There is no sign-convention trap here, unlike PED.