Definition and Mechanism
Purchasing Power Parity (PPP) is a method of currency conversion that accounts for differences in price levels across countries. It calculates the exchange rate at which the same basket of goods and services would cost the same amount in each country, equalizing real purchasing power.
Difference from Market Exchange Rates
Market exchange rates fluctuate daily based on financial trading and speculation, while PPP rates reflect actual price levels in the real economy. Developing countries tend to have market rates below their PPP rates, meaning market-rate conversions understate their true living standards.
For example, India's per capita GDP is about $2,500 at market exchange rates but approximately $9,000 in PPP terms, providing a more accurate picture of actual living conditions.
The ICP Survey in Practice
The International Comparison Program (ICP), led by the World Bank, surveys prices of thousands of items across roughly 180 countries to calculate PPP rates. Surveys are conducted approximately every six years, with interim years filled by estimates. Item selection and quality adjustments present ongoing challenges.
Why MyRank Uses PPP
MyRank's income rankings adopt PPP conversion to fairly evaluate the real prosperity of people living in lower-cost countries. Someone earning the equivalent of $20,000 in a country where prices are one-third of Japan's has purchasing power comparable to a $60,000 earner in Japan. PPP makes this visible.