A new index reveals a widening gap between growth and sustainable wellbeing in China

Previous wellbeing measures often aggregate economic, social, and environmental dimensions, assuming full substitutability. We propose a new index—Sustainable Wellbeing (SW)—that integrates Wellbeing Magnitude (WM) and Wellbeing Diversity (WD). This index reflects that positive wellbeing sources increase SW, with diminishing marginal returns, while negative wellbeing sources decrease SW, with increasing marginal damage. Both diversity and magnitude are integral to the index. This framework is applicable to many wellbeing indices. We demonstrate the application of SW using the Genuine Progress Indicator (GPI) for China, creating a revised Sustainable GPI (SGPI) that incorporates WD. An evaluation across China's 31 provinces from 1985 to 2018 shows a decline in WD, leading to a growing gap between sustainable wellbeing and economic growth. Economic wellbeing has expanded at the expense of environmental quality. The SGPI-to-GDP ratio displays an inverted U-shaped curve, reflecting limited substitutability between economic and environmental wellbeing beyond a certain income threshold. Provinces with stronger service sectors experienced the highest per capita SGPI growth. The wellbeing diversity framework supports balanced development and aligns with the Sustainable Development Goals (SDGs).