Purchasing Power Parity
Purchasing Power Parity (PPP) is an economic theory and measurement framework that compares the purchasing power of different currencies by equalising the cost of an identical basket of goods and services across countries, enabling more accurate cross-country comparisons of economic output and living standards.
The simplest illustration of PPP was the Economist magazine's Big Mac Index, which compared the price of a McDonald's Big Mac hamburger across countries as a proxy for the broader price level. The underlying logic was that if exchange rates were in perfect equilibrium, an identical good should cost the same in every country when prices were converted to a common currency. If a Big Mac cost USD 5.69 in the USA but the equivalent of USD 2.50 in India (at market exchange rates), the Indian rupee was undervalued relative to its PPP rate by approximately 56 percent.
For national accounting purposes, PPP-adjusted GDP was computed using price surveys across hundreds of goods and services categories in each country, coordinated through the International Comparison Programme (ICP) managed by the World Bank and other international organisations. The ICP produced PPP conversion factors that allowed meaningful comparisons of real living standards across economies with very different price levels.
India's GDP at PPP was substantially larger than India's GDP at market exchange rates. In 2024–25, India's nominal GDP at market exchange rates was approximately USD 3.7–4.0 trillion, making it the fifth or sixth largest economy globally. At PPP, India's GDP was approximately USD 14–15 trillion, making it the third largest economy in the world, after the USA and China. The difference arose because the prices of non-tradeable goods and services — haircuts, construction labour, domestic food — were much lower in India than in the USA or Europe, so the real quantity of goods and services Indians consumed was considerably larger than the dollar-denominated figures suggested.
For investors and analysts, PPP was relevant in several contexts. Multinational companies used PPP-based metrics to assess the real size of consumer markets and the real purchasing power of target demographics. A per capita income of USD 2,500 in India, when PPP-adjusted to approximately USD 8,500, implied a middle-class consumer with meaningfully more real purchasing power than the nominal figure suggested. This PPP-based view was one factor behind the sustained investment interest of global consumer goods companies — Unilever, P&G, Nestlé, Apple — in the Indian market.
For exchange rate theory, relative PPP (as opposed to absolute PPP) stated that over the long run, exchange rates adjusted to maintain purchasing power parity — meaning a country with higher inflation should see its currency depreciate relative to low-inflation countries at a rate approximately equal to the inflation differential. The Indian rupee had depreciated against the US dollar at a long-run average of approximately 3–4 percent per year, broadly consistent with India's higher inflation relative to the USA, providing empirical support for the relative PPP framework over long time horizons.