As per International Monetary Fund (IMF) 2019 estimates, the GDP (nominal) of Saudi Arabia is USD 779,289 million. This GDP (nominal) is around 0.89% of Entire World’s GDP. Currently (2019), the world rank of Saudi Arabia is 18 in terms of GDP Nominal.
However, as per 2018 estimates by World Bank, the GDP (Nominal) of Saudi Arabia is USD 782,483 million. As per World Bank Estimates, the global rank of Saudi Arabia is 18.

Saudi Arabia GDP [PPP]

On the other hand, as per 2019 estimates by International Monetary Fund, the GDP (PPP) of Saudi Arabia is USD 1,898,511 Million. This is 1.34% of World. Saudi Arabia on this basis has a global rank of 17.