Hundreds of millions of children are losing learning opportunities resulting in potentially large losses in their lifetime education, health, income, and productivity. Losses in long-term incomes from preprimary program closures due to COVID-19 can be unprecedented. This study is the first to simulate losses due to preprimary program closures because of the COVID-19 pandemic on the discounted values of future earnings when current preschool age children become adults for 140 countries. These losses are considerable in comparison with governmental expenditures on all levels of education in the same countries. Policies need to mitigate the effects of preprimary program closures to avoid these enormous losses.