Background: A series of policies aimed toward rational resource allocation of long‐term care have being actively discussed since the launch of the social long‐term care insurance in Shanghai, and it is important to take a societal perspective for informed decision‐making. Objectives: This study aims to explore factors that are associated with well‐being of informal caregivers in Shanghai, and to provide empirical evidence of application of an established well‐being valuation method to monetise informal caregivers' well‐being losses in a developing country. Methods: 310 informal caregivers of applicants for social long‐term care insurance in Shanghai were interviewed. Univariate and multivariate analyses were conducted to explore the associated factors with life satisfaction of the caregivers. The monetary values of an additional hour of caregiving with and without specification of care tasks were estimated by the well‐being valuation method. Results: Life satisfaction was consistently associated with monthly income, health status, and caring hours of the caregivers. The money needed to compensate one additional hour of caring per week was 12.58 CNY (0.3% of the monthly income), and 96.95 CNY (2.0% of the monthly income) for activities of daily living (ADL) tasks. Income, health status, and caregiving are significantly associated with well‐being of informal caregivers. Conclusions: Caregivers in relatively poor health condition and/or involved in more ADL tasks should be particularly considered in supporting policies in Shanghai.