An informal measure of purchasing power parity created by The Economist magazine, comparing the price of a McDonald's Big Mac across countries to estimate whether currencies are overvalued or undervalued against the dollar.
What the Big Mac Index Shows
The Big Mac Index, published by The Economist since 1986, uses the price of a McDonald's Big Mac hamburger as a benchmark for Purchasing Power Parity (PPP). If a Big Mac costs $5.50 in the U.S. and the equivalent of $4.00 in another country, the index suggests that country's currency is approximately 27% undervalued against the U.S. Dollar (USD).
Why the Big Mac Works as a PPP Proxy
The Big Mac is available in over 100 countries and contains a consistent set of ingredients (beef, bread, lettuce, cheese, sauce) that must be locally sourced. This makes it a rough proxy for local production costs, wages, rent, and other factors that determine price levels. The index captures differences in purchasing power in a simple, relatable way.
The Economist also publishes a GDP-adjusted version that accounts for the fact that poorer countries tend to have lower prices even when purchasing power is considered.
Limitations
The Big Mac Index does not account for differences in local taxes, labor regulations, import duties on ingredients, or the fact that McDonald's adjusts prices for local market conditions. It is best used as an illustrative tool rather than a precise valuation metric.
Related Terms
Purchasing Power Parity (PPP)
An economic theory stating that exchange rates should adjust so that identical goods cost the same in different countries when priced in a common currency. PPP provides a long-term benchmark for assessing whether currencies are overvalued or undervalued.
Exchange Rate
The price of one currency expressed in terms of another currency. EUR/USD at 1.0850 means 1 euro equals 1.0850 US dollars.
Inflation
A sustained increase in the general price level of goods and services, reducing purchasing power. Central banks target specific inflation rates (typically 2%) and adjust monetary policy to achieve that target.
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