Inelastic demand is a term used to describe the unchanging quantity of a good or service when its price changes.

Perfectly Inelastic Supply Perfectly inelastic supply is when the PES formula equals zero. That is, there is no change in quantity supplied when the price changes.

An elastic demand curve means that a change in price has a large effect on buying, while an inelastic demand curve means that a price change has less effect on buying.

Perfectly Inelastic Supply Perfectly inelastic supply is when the PES formula equals zero. That is, there is no change in quantity supplied when the price changes.