The Big Mac Index
A tasty exchange rate tool that compares local price levels and currency values across the globe using the exact same burger.
Definition An informal economic indicator that compares the purchasing power of different currencies by converting the local price of a McDonald's Big Mac into US dollars. Published annually by The Economist, it provides a simple way to gauge whether market exchange rates are fairly valued.
Why Choose a Burger as the Benchmark?
When traveling abroad, you have probably stepped into a familiar fast-food restaurant to grab a meal. A Big Mac uses virtually identical ingredients and cooking methods around the worldโbuns, beef patties, cheese, lettuce, pickles, and special sauce.
In economics, a core principle known as the 'Law of One Price' states that identical goods should cost the same anywhere in the world when priced in a common currency. The globally standardized Big Mac serves as the ideal benchmark product to test this theory.
For example, if a Big Mac costs $5.00 in the US and 5,000 KRW in South Korea, the implied equilibrium exchange rate should be 1,000 KRW per dollar. Using a single burger as a yardstick reveals the true purchasing power of a currency in a way anyone can intuitively grasp.
How to Tell if a Currency is Overvalued or Undervalued
By comparing the actual exchange rate traded in currency markets with the implied rate calculated from a burger, you can see whether a currency is fairly priced. For instance, if a Big Mac costs $5.00 in the US and 6,500 KRW in Korea, the implied fair exchange rate is 1,300 KRW per dollar.
What if the actual market rate at the bank today is 1,400 KRW per dollar? That means the market is pricing the Korean won cheaper than its actual burger-purchasing value suggests. In this scenario, the won is considered 'undervalued'.
Conversely, if the actual market rate is 1,200 KRW per dollar, the won holds more market value than its baseline purchasing power, making it 'overvalued'. In this way, a single burger gives you an immediate picture of which way a currency is leaning.
A Closer Look: The Limitations of the Big Mac Index
While the Big Mac Index is clever and intuitive, it is not a flawless exchange rate calculator. That is because burger prices reflect far more than just beef and bunsโthey also carry substantial non-tradable costs such as store rent, worker wages, and local business taxes.
In developing countries where labor and commercial rent are relatively low, producing and selling a Big Mac costs far less than in wealthy nations. As a result, currencies of lower-income nations almost always show up as heavily undervalued under the index.
Differences in brand positioning and food culture also matter. In some countries, McDonald's is an everyday budget snack, while in others, it is viewed as a special dining treat. For these reasons, the Big Mac Index is best used as a helpful reference point for currency trends rather than a rigorous economic metric.
๐ค Common misconceptions
The Big Mac Index is an official economic statistic used by central banks to set exchange rates.
It is an informal guide designed to explain purchasing power parity in a lighthearted way. Local differences in commercial rent, labor costs, and sales taxes create natural gaps between burger prices and real market rates.
๐งบ Where you meet it
The Big Mac Index compares global burger prices to make real purchasing power and currency valuation easy to understand.