The Health Utilities Index (HUI) is a rating scale used to measure general health status and health related quality of life (HRQoL). HUI questionnaires are designed to map onto two classification systems, HUI-2 and HUI-3, capable of measuring 24,000 and 972,000 unique health states, respectively. HUI classifications measure a range of health domains with examples including sensation, mobility, pain, cognition, ambulation, and emotion. Health utility values are commonly produced using HUI as a component of the quality-adjusted life years (QALY) calculation used in population health and economics.