Price Elasticity of Demand

P E_{D} = \frac{C D}{C P}

$PE_D = ( CD )/( CP )$

(C D) Change in Quantity Demanded

$(CD)"Change in Quantity Demanded"$

(C P) Change in Price

$(CP)"Change in Price"$

The Math / Science

The formula for Price Elasticity of Demand is:

PED = CD / CP

where:

PED = Price Elasticity of Demand
CD = Percent Change in Quantity Demanded
CP = Percent Change in Price

Note: A more reliable way to compute price elasticity of demand is via the Midpoint Method. The formula for Midpoint Method of Price Elasticity of Demand is:

$P E D = \frac{(Q_{2} - Q_{1}) \div (Q_{2} + Q_{1}) / 2}{(P_{2} - P_{1}) \div (P_{2} + P_{1}) / 2} = \frac{Percent Change in Quantity}{Percent Change in Price}$ $PED = ((Q_2 - Q_1) ÷ (Q_2 + Q_1)"/"2) / ((P_2 - P_1) ÷ (P_2 + P_1)"/"2) = ("Percent Change in Quantity")/("Percent Change in Price")$

where:

PED is the Price Elasticity of Demand
P₁ this is the first price point
P₂ this is the second price point
Q₁ is the quantity point associated with the first price point (P₁)
Q₂ is the quantity point associated with the second price point (P₂)

Macroeconomics Calculators

Micro Economics Calculators

Basic Price Elasticity of Demand.
Midpoint Method of Price Elasticity of Demand
Midpoint Method of Price Elasticity of Demand with automatic Quantity Unit Handling:
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Reference:

Mankiw, N. Gregory. "Chapter 5:The Elasticity of Demand." Principles of Macroeconomics. 6th ed. Mason, OH: Thomson/South-Western, 2004. 91. Print.
“Chapter 7 Consumer Choice and Elasticity.” AP Microeconomics 2018, by Eric R. Dodge, McGraw Hill Education, 2017.