Ersatzgut

Ersatzgut, in economics, is a substitute good—a product that can take the place of another in a consumer’s use. Substitutes arise when two goods satisfy similar needs or have overlapping uses, so changes in the price or availability of one influence the demand for the other. The degree of substitutability varies: some substitutes are nearly perfect, so a small price change shifts demand almost entirely; others are imperfect, sharing only parts of a function or differing in quality, brand, or convenience.

Economists measure substitutability with cross-price elasticity of demand: a positive cross-price elasticity indicates that the goods are substitutes, while a larger magnitude signals closer substitution.

Common examples include coffee and tea, butter and margarine, or different brands of cola. In times of shortage, Ersatzgut commonly refers to replacement goods supplied to substitute scarce items, such as chicory-based coffee substitutes or other processed products used during rationing.

Substitution affects market outcomes, influencing price competition, consumer welfare, and production decisions. Firms facing high substitutability may compete more aggressively on price, quality, or branding. Policy considerations include how substitutes affect demand for regulated goods and overall efficiency.

The term highlights how households adapt to price changes and scarcity by shifting consumption to alternatives that satisfy similar needs.