Utilizing economic tools, we evaluate the gains from improving the relationship between biological and chronological age in dollar terms. We show that the gains to individuals are substantial because targeting aging exploits synergies between health and life expectancy and the complementarities across different diseases. Gains are boosted by improvements in life expectancy and a rising number of older people. We compute the value of slowing aging in a range of countries and estimate that increasing life expectancy by 1 year has an annual benefit of ∼4%–5% of gross domestic product (GDP). Augmenting GDP with these measures of health gains reveals the growing importance of achieving healthy longevity as a means of boosting welfare, with the need being particularly acute in the United States.