List of countries by GDP (PPP)

GDP methodology

GDP dollar estimates for all countries are derived from purchasing power parity (PPP) calculations rather than from conversions at official currency exchange rates. The PPP method involves the use of standardized international dollar price weights, which are applied to the quantities of final goods and services produced in a given economy. The data derived from the PPP method provide the best available starting point for comparisons of economic strength between countries. The division of a GDP estimate in domestic currency by the corresponding PPP estimate in dollars gives the PPP conversion rate. Whereas PPP estimates for OECD countries are quite reliable, PPP estimates for developing countries are often rough approximations. Most of the GDP estimates are based on extrapolation of PPP numbers published by the UN International Comparison Program (UNICP) and by Professors Robert Summers and Alan Heston of the University of Pennsylvania and their colleagues. In contrast, the currency exchange rate method involves a variety of international and domestic financial forces that often have little relation to domestic output. In developing countries with weak currencies the exchange rate estimate of GDP in dollars is typically one-fourth to one-half the PPP estimate. Furthermore, exchange rates may suddenly go up or down by 10% or more because of market forces or official fiat whereas real output has remained unchanged. On 12 January 1994, for example, the 14 countries of the African Financial Community (whose currencies are tied to the French franc) devalued their currencies by 50%. This move, of course, did not cut the real output of these countries by half. One important caution: the proportion of, say, defense expenditures as a percentage of GDP in local currency accounts may differ substantially from the proportion when GDP accounts are expressed in PPP terms, as, for example, when an observer tries to estimate the dollar level of Russian or Japanese military expenditures.

See also

• List of countries by GDP (nominal) - GDP with currencies converted at market exchange rates.
• List of countries by GDP (PPP) per capita - GDP at purchasing power parity (PPP) exchange rates per habitant
• List of countries by GDP (nominal) per capita - GDP at market or government official exchange rates per habitant