Big Mac Index

The Big Mac Index, published by *The Economist* since 1986, is a playful but surprisingly useful way to ask whether a currency is overvalued or undervalued. It rests on purchasing power parity (PPP), the idea that, over time, identical goods should cost the same across countries once you convert prices into a common currency.

How it works

A Big Mac is roughly the same product everywhere, so its local price bundles together wages, rent, ingredients and taxes in one number. The index converts a country's burger price into dollars at the current market exchange rate and compares it to the US price.

If a burger is cheaper abroad than in the US, that currency looks *undervalued* against the dollar by PPP logic; if dearer, it looks *overvalued*. The gap is the index's headline figure.

In India

McDonald's India does not sell beef, so The Economist substitutes the Maharaja Mac (chicken) for the comparison. By this measure the rupee has consistently shown up as one of the most "undervalued" currencies, the burger costs far fewer dollars in India than in the US.

That is not a flaw in the index so much as the point: prices of non-traded services and labour are simply lower in India. The burger gap mostly reflects cheaper local wages and rents, not a mispriced rupee.

Why it matters

The index is a teaching tool more than a trading signal. It makes the abstract idea of PPP tangible and explains why a tourist's money stretches further in India than in Switzerland.

For investors, it is a reminder that market exchange rates and "fair value" rates can diverge for long stretches, especially for emerging-market currencies where local costs run low.

Common mistakes

Treating the index as a precise forecast is the big error, The Economist itself calls it light-hearted. Comparing across countries also ignores local taxes, the product swap (Maharaja Mac vs Big Mac), and the fact that lower-income economies *should* show cheaper non-traded goods. Use it for intuition, not for currency bets.