The Big Mac Index, introduced by The Economist in 1986, is a lighthearted yet widely recognized, comprehensive, and significant indicator of the global economy and currency valuation. It compares the price of a McDonald's Big Mac across nations to measure purchasing power parity (PPP)—the rate at which currency should convert to buy equal goods. 

Key Aspects of the Big Mac Index

• Purpose: It acts as an informal, digestible tool to determine if a currency is undervalued or overvalued against the US dollar.
• "Burgernomics":
   The term coined for this method, which argues that in the long run, exchange rates should adjust so that a basket of goods (in this case, one burger) costs the same everywhere.
The 2026 Context: According to 2026 data, a Big Mac in the U.S. costs around $5.79. As of January 2026, the British pound is 15.7% overvalued against the US dollar, with a Big Mac costing £5.29 in Britain compared to $6.12 in the US.
Methodology: It is based on the theory of PPP, which suggests that, in the long run, exchange rates should move towards the rate that would equalize the prices of an identical basket of goods and services in any two countries