Pre-print, Working paper: The equivalent income is a preference-based, interpersonally comparable measure of well-being. Although its theoretical foundations are well-established, empirical applications remain limited, primarily due to the detailed data requirements on individuals' preferences across various wellbeing dimensions. This paper reviews the literature on preference elicitation methods with a focus on estimating equivalent income. We examine several survey-based methods, including contingent valuation, multi-attribute choice or rating experiments, and life satisfaction regressions. The review highlights the advantages and limitations of each method, emphasizing the considerable scope for methodological improvements and innovations.