Deadweight Loss Calculator — Market Efficiency Loss
Calculate the deadweight loss — the value destroyed when a market intervention (tax, price floor, ceiling, or monopoly) pushes the actual price away from the competitive equilibrium. Input the equilibrium price and quantity, the new distorted price, and the price elasticities of supply and demand.
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$
Efficiency loss — value destroyed by the market distortion
- 1
Price change (ΔP)
13 − 10 = 3 - 2
% price change
3 ÷ 10 = 0.3 - 3
Quantity change from demand
-1.5 × 0.3 × 100 = -45Negative because price rose; quantity demanded falls. - 4
Quantity reduction (|ΔQ|)
45 - 5
Deadweight loss
½ × 3 × 45 = 67.50
How does this calculator work?
Deadweight loss = ½ × |ΔP| × |ΔQ|. Enter the competitive equilibrium price and quantity, the intervention price, and supply/demand elasticities; the calculator derives the quantity reduction using %ΔQ = elasticity × %ΔP and returns the triangle area representing wasted economic surplus.
Formula
How this is calculated
In a competitive market, the equilibrium price and quantity maximise the total surplus (consumer surplus plus producer surplus). Any intervention that sets a different price causes some mutually beneficial trades to not occur — the forgone surplus is the deadweight loss.
The magnitude of the DWL depends on how much the price shifts (ΔP) and how responsive buyers and sellers are to that shift — captured by the price elasticities of demand and supply. Using the point-elasticity formula (%ΔQ = elasticity × %ΔP) the calculator derives the new quantities supplied and demanded at the distorted price, then uses ΔQ = Qeq − min(Qs, Qd) to find the quantity reduction. The deadweight loss is the area of the resulting triangle: ½ × |ΔP| × |ΔQ|.
This model assumes linear supply and demand curves around the equilibrium point, which is a good approximation for small to moderate price changes. For large interventions or highly non-linear markets the triangle formula understates the true welfare loss. The calculator uses stated values and does not account for externalities, second-round price effects, or general-equilibrium feedback — treat results as illustrative order-of-magnitude estimates.
Frequently asked questions
Any wedge between the price a buyer pays and the price a seller receives — taxes, tariffs, price floors (minimum wages), price ceilings (rent controls), or monopoly mark-ups — prevents trades that would benefit both parties. Those forgone trades are the deadweight loss.
Yes, larger ΔP always increases DWL, but the relationship is convex: DWL grows with the square of the tax rate. Double the tax rate → roughly quadruple the DWL. More elastic markets (higher |Ed| or Es) amplify the quantity response and make DWL even larger.
DWL is measured in the same currency units as the price (e.g. dollars). The formula ½ × ΔP × ΔQ gives currency × quantity = total value. Make sure price and quantity are consistent (e.g. price per unit and number of units).
Also known as
TG we-Calculate Editorial Team. (2026). Deadweight Loss Calculator — Market Efficiency Loss [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/deadweight-loss-calculator
TG we-Calculate Editorial Team. "Deadweight Loss Calculator — Market Efficiency Loss." TG we-Calculate. 2026. https://we-calculate.com/calculator/deadweight-loss-calculator.
TG we-Calculate Editorial Team, "Deadweight Loss Calculator — Market Efficiency Loss," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/deadweight-loss-calculator
@misc{wecalculate_deadweight_loss_calculator, title = {Deadweight Loss Calculator — Market Efficiency Loss}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/deadweight-loss-calculator}}, year = {2026}, note = {TG we-Calculate} }
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