A research team led by Seth Flaxman at Imperial College London reached the figure by using birth rate and coronavirus mortality data to create mathematical models.
Because the data are not collected as comprehensively in all places, the figure can only be an approximation, and is probably an underestimate, the scientists wrote.
The number of children who lost one or both parents due to the pandemic is particularly high in relation to the population in South Africa, Mexico, Brazil and Colombia, among other countries.
Overall, the number of children who have lost fathers is about five times higher than the number of children who have lost mothers.
The study was published in The Lancet medical journal.