Fast fashion refers to a strategy to respond to the latest fashion trends by short production and distribution lead times, limited supplies and rapid inventory turnover rates. Whilst research on fast fashion mostly investigates producers’ side, e.g. supply chain, scholarship exploring consumers’ side of fast fashion remains limited. In addition, research on fast fashion consumption tends to neglect similarities and differences of consumers (e.g. needs, wants, desires, and demographic characteristics) in different parts of the world, particularly developed and developing economies. The aim of this study is threefold: Firstly, by focusing on the emergent Turkish market and the established Finnish market, it analyses and compares fast fashion consumption of Turkish and Finnish consumers. Secondly, through qualitative and quantitative studies, it reveals the components of fast fashion consumption, which include appearance management, repeat visiting behavior, product use duration, interaction with social media, impulse buying, willingness to pay full price, hedonic consumption, and fashion involvement, and develops a scale for measuring fast fashion consumption. Thirdly, it evaluates the impact of each component and examines the influence of demographic variables on fast fashion consumption. The findings demonstrate both personal and national differences in the components of fast fashion and point to a need for an in-depth, cross-cultural study on ethical and environmental issues related to fast fashion consumption.