Definition
An economic benchmark that compares the price of a Big Mac across different countries by converting local burger prices into US dollars. Created by the British magazine The Economist in 1986 and published twice a year (January and July), it helps people easily see the real purchasing power of different currencies and whether market exchange rates are fair.
Why use a burger as a global benchmark?
Most travelers have walked into a familiar fast-food restaurant abroad to grab a quick meal. A Big Mac uses nearly identical ingredients and recipes worldwide: two beef patties, special sauce, lettuce, cheese, pickles, and onions on a sesame seed bun. (In India, where beef is widely avoided, the chicken Maharaja Mac is used instead).
In economics, there is a foundational concept known as the law of one price: identical goods should cost the same everywhere once their prices are converted into a common currency. As a globally standardized product, the Big Mac is an ideal test case for this rule.
If a Big Mac costs $5 in the United States and 5,000 won in South Korea, the two currencies should balance out to an exchange rate of 1,000 won per dollar. By using a burger as a ruler, it reveals the real purchasing power of money in a way anyone can immediately grasp.
How to tell if a currency is overvalued or undervalued
Comparing the actual foreign exchange rate to the implied burger rate shows whether a currency trades above or below its true purchasing power. For instance, if a US Big Mac costs $5 and a Korean Big Mac costs 6,500 won, the implied fair exchange rate is 1,300 won per dollar.
Now imagine the actual bank exchange rate today is 1,400 won per dollar. In the open market, the won trades for less than its burger-buying power suggests. Economists describe this currency as undervalued.
On the flip side, if the actual rate is 1,200 won per dollar, the won trades higher than its burger-implied worth, meaning it is overvalued. A single burger lets you quickly see which way an exchange rate leans.
To be precise: The limits of the Big Mac Index
To be precise, while the Big Mac Index is intuitive and fun, it is not a perfect exchange-rate model. A burger's price reflects far more than the raw ingredients. It includes substantial non-tradable costs such as store rent, worker wages, and local sales taxes.
In developing countries where labor and commercial rent are cheaper, a Big Mac costs far less to produce than in wealthy nations. As a result, currencies from lower-income countries often appear artificially undervalued. To address this, The Economist also publishes a GDP-adjusted Big Mac Index that accounts for national income levels.
Brand positioning and local dining habits also vary. In some countries, McDonald's is an inexpensive snack; in others, it is viewed as a special dining treat. For these reasons, the Big Mac Index serves best as a fun rule of thumb rather than a rigid financial tool.
Common misconceptions
The Big Mac Index is an official exchange-rate model used by central banks.
The Big Mac Index is an informal guide created for general audiences. Differences in local store rent, labor costs, and tax policies naturally cause it to diverge from market exchange rates.
Where you meet it
Before a trip abroad, you can check local Big Mac prices to get a quick feel for whether daily expenses will feel cheaper or more expensive than back home.
When financial news notes that 'a currency is 10% undervalued on the Big Mac Index,' it means the currency trades 10% lower on foreign exchange markets than burger price parity implies.
In one sentence
The Big Mac Index compares the price of a standard burger around the globe to help people easily understand real purchasing power and currency exchange rates.