The World Bank has used the Atlas method since 1993 to estimate the economic size of countries based on their gross national income (GNI) in U.S. dollars.

To convert a country's GNI from its local currency to U.S. dollars, the Atlas method uses a conversion factor that averages exchange rates over three years. This helps reduce the impact of temporary exchange rate changes. Additionally, it adjusts for differences in inflation rates between the country (using its GDP deflator) and several developed countries (using a weighted average of their GDP deflators in Special Drawing Rights, or SDR, terms). The converted GNI in U.S. dollars is then divided by the country's midyear population to determine GNI per capita.

The World Bank prefers the Atlas method for comparing the economic sizes of countries. It is used to categorize countries into low, middle, and high-income groups and to determine their eligibility for loans. This method helps avoid abrupt changes in country classification due to short-term economic fluctuations.