Circular economy brings environmental, economical and social benefits to the society. New business initiatives are encouraged to accelerate the shifting towards a circular economy. However, the scaling of new business in the circular economy is still under-researched. This study is focused on the demand aspect of business scaling, and aims to propose a holistic framework to estimate the market potential for a new business in the circular economy. The framework is composed of sets and filters, where demand forecast is deduced from the statistics of existing products and secondary market research. Quantitative and qualitative methods are both used in the framework, where clustering analysis and multi-criteria decision-making techniques are combined with expert judgement. A case study on electric retrofit of vehicles is proposed to demonstrate the application of the framework