deadweight loss

In economics , a deadweight loss (also known as excess burden or allocative inefficiency ) is a loss of economic efficiency that can occur when equilibrium for a good or service is not Pareto optimal . In other words, either people who would have more marginal benefit than marginal cost are not buying the product, or people who have more marginal cost than marginal benefit are buying the product. Deadweight loss can be beneficial when there is a negative externality , in which case it can be considered a deadweight gain , as it would help those that the negative externality was hurting.