An adjusted life year is a measure of the value of a year of life adjusted in ways relevant for moral or medical valuation.

The most commonly used types of adjusted life year are quality-adjusted life years (QALYs) and disability-adjusted life years (DALYs). Both QALYs and DALYs fall under the broader category of health-adjusted life years (HALYs), which rely on measures of health to make the relevant adjustments. HALYs are commonly used in public health to quantify the burden of disease and to compare the cost-effectiveness of different health interventions. By contrast, wellbeing-adjusted life years (WALYs) adjust based on measures of wellbeing, such as hedonic experience or preference satisfaction. One type of WALY is the WELLBY, which measures wellbeing on a scale ranging from 0 to 10, representing the answers "not at all" and "completely", respectively, to the question "Overall, how satisfied are you with your life nowadays?"^[1] Within the effective altruism community, WALYs are generally preferred over HALYs, because things other than health can contribute to a person's wellbeing, and because health itself, while often a good proxy for wellbeing, is not generally regarded as intrinsically valuable.^[2]