Point elasticity is the price elasticity of demand at a
specific point on the demand curve instead of over a range of the demand curve. It uses the
same formula as the general price elasticity of demand measure, but we can take
information from the demand equation to solve for the “change in” values
instead of actually calculating a change given two points. Here is the process to find the point
elasticity of demand formula:

Point Price Elasticity of Demand = (% change in Quantity)/(% change in Price)
Point Price Elasticity of Demand = (∆Q/Q)/(∆P/P)

Point Price Elasticity of Demand = (P/Q)(∆Q/∆P)

Where (∆Q/∆P) is the derivative of the demand function with respect to P. You don’t really need to take the derivative of the demand function, just find the coefficient (the number) next to Price (P) in the demand function and that will give you the value for ∆Q/∆P because it is showing you how much Q is going to change given a 1 unit change in P. Finding the point elasticity solution is best demonstrated with examples...

Point Price Elasticity of Demand = (% change in Quantity)/(% change in Price)

Point Price Elasticity of Demand = (P/Q)(∆Q/∆P)

Where (∆Q/∆P) is the derivative of the demand function with respect to P. You don’t really need to take the derivative of the demand function, just find the coefficient (the number) next to Price (P) in the demand function and that will give you the value for ∆Q/∆P because it is showing you how much Q is going to change given a 1 unit change in P. Finding the point elasticity solution is best demonstrated with examples...