The Big Mac inspired the name of The Economist's Big Mac Index.
The index uses the price of a Big Mac in different countries as an informal way to compare purchasing power and currency valuation. The sandwich was chosen because McDonald's operates internationally and the product has a broadly standardized recipe, making it a familiar reference across markets.
The Big Mac Index is a branding afterlife: a McDonald's product name became shorthand for a widely discussed economic comparison. It is not an official measure created by McDonald's, and it is not a complete substitute for professional economic indicators.
The index was introduced by The Economist in 1986. It is often confused with the Big Mac's introduction date, which was 1968. The product predates the index by nearly two decades and had already become one of McDonald's most recognizable branded items.