According to the latest statistics released by the World Bank in 2025, among the OPEC countries in 1978, Saudi Arabia ranked first in terms of gross domestic product(GDP), with a total economic volume of $80.27 billion; Iran ranked second in terms of GDP, with a total economic volume of $77.99 billion; Venezuela ranked third in terms of GDP, with a total economic volume of $39.32 billion; Nigeria ranked fourth in terms of GDP, with a total economy of $36.53 billion; and Algeria, with a total economy of $26.36 billion, ranked fifth in GDP.
| Rank | Country | GDP |
|---|---|---|
| 1 | Saudi Arabia | $80.27 billion |
| 2 | Iran | $77.99 billion |
| 3 | Venezuela | $39.32 billion |
| 4 | Nigeria | $36.53 billion |
| 5 | Algeria | $26.36 billion |
| 6 | United Arab Emirates | $23.78 billion |
| 7 | Iraq | $23.76 billion |
| 8 | Kuwait | $15.5 billion |
| 9 | Gabon | $2.39 billion |
| 10 | Republic of Congo | $0.88 billion |