Reading Exchange Rates with the Big Mac Index
What if you could gauge whether an exchange rate is fair using a single hamburger sold anywhere in the world? That is exactly the idea behind the 'Big Mac Index,' which The Economist started almost as a joke in 1986.
Measuring exchange rates with a hamburger?
The Big Mac Index is an informal exchange-rate gauge created in 1986 by the British economics magazine The Economist. By comparing the price of a Big Mac sold at McDonald's around the world, it roughly estimates whether each country's currency is over- or under-valued against the dollar.
The underlying idea is purchasing power parity (PPP). It is the principle that 'the same item should cost roughly the same in any country (once converted at the exchange rate).' Since the Big Mac is sold with nearly the same specification worldwide, it is a perfect 'standard product' for illustrating PPP visually.
The Economist itself introduces the Big Mac Index as a 'light-hearted educational tool.' It is not a precise exchange-rate forecaster.
This is how you read over- and under-valuation
The method is simple. Take the local price of a Big Mac in a given country, convert it to dollars at the current exchange rate, and compare it with the U.S. Big Mac price.
For example, as of January 2026, a Korean Big Mac was about 5,500 won, which converted at the exchange rate at the time was about $3.7. Since it was noticeably cheaper than the U.S. Big Mac at the same point, by this calculation the won appeared roughly 39% 'undervalued' against the dollar. In other words, 'on a hamburger basis, the won is priced cheaper than the actual exchange rate.' Conversely, a country like Switzerland where the Big Mac is far more expensive than in the United States shows up as having an 'overvalued' currency.
This is an example based on the exchange rate at a specific point in time. When exchange rates and local prices change, the result changes too, so the figures shift with each release.
Fun, but the limits are clear
There are many reasons you should not take the Big Mac Index at face value.
First, a Big Mac's price includes not just ingredient costs but also large amounts of local rent, labor, and taxes. In a country with cheap labor, the Big Mac is cheap too, making the currency look 'undervalued'—but this is due to that country's price structure, not an exchange-rate issue.
Second, it is a gauge based on a single Big Mac, so its scope is too narrow, and Big Mac specifications and dietary habits differ slightly by country.
Third, actual exchange rates move due to countless factors such as interest rates, current account balances, geopolitics, and investor sentiment, none of which the Big Mac Index captures, so its predictive power is weak. The fact that The Economist later introduced a 'GDP-adjusted version' reflecting income levels was an attempt to partly address these limits.
Frequently Asked Questions
Q. If a currency shows up as undervalued, will it rise soon?
You cannot conclude that. The Big Mac Index's 'undervaluation' is at best a rough estimate based on hamburger prices, and actual exchange rates move due to far more complex factors. Many currencies stay undervalued for years. It is far too simple a gauge to use as a basis for investment decisions.
Q. Why specifically the Big Mac?
Because the Big Mac is a rare standard product sold in over 100 countries worldwide with nearly identical ingredients and cooking methods. Such comparison is difficult with products whose specifications differ greatly by country. Of course, it is still not a perfectly identical item, which remains a limitation.
Related pages
📋 Results are based on historical data; past returns do not guarantee future returns.
📋 This service is provided for educational purposes to help you understand investing, not as investment advice.