Objective: We compare population aging in Europe and Asia using a measure that is both consistent over time and appropriate for cross-country comparison. Method: Sanderson and Scherbov proposed to estimate the old-age threshold by the age at which the remaining life expectancy (RLE) equals 15 years. We propose an adjustment of this measure, taking into account cross-national differences in the exceptionality of reaching that age. Results: Our old-age threshold was lower than 65 years in 2012 in Central Asia, Southern Asia, Southeastern Asia, and many Eastern European countries. These populations also experienced a higher share of elderly compared with the RLE15 method. Our method revealed more geographical diversity in the shares of elderly. Both methods exhibited similar time trends for the old-age thresholds and the shares of elderly. Discussion: Our prospective and comparative measure reveals higher population aging estimates in most Asian and Eastern European countries and more diversity in aging.