Purpose This study aims to clarify the effects of different patterns of Facebook, Twitter and Instagram usage on user loneliness and well-being in Japan. Design/methodology/approach Based on responses to a self-report questionnaire in Japan, 155 university students were separated into 4 groups: users of Twitter only, users of Twitter and Facebook, users of Twitter and Instagram and users of all three social media. The effects of social media usage on loneliness and well-being for each group were analysed. Findings No social media usage effects on loneliness or well-being were detected for those who used only Twitter or both Twitter and Instagram. For those using both Twitter and Facebook, loneliness was reduced when users accessed Twitter and Facebook more frequently but was increased when they posted more tweets. Users of all three social media were lonelier and had lower levels of well-being when they accessed Facebook via PC longer; whereas their their access time of Facebook via smartphones helped them decrease loneliness and improve their levels of well-being. Originality/value The findings reported here provide possible explanations for the conflicting results reported in previous research by exploring why users choose different social media platforms to communicate with different groups of friends or acquaintances and different usage patterns that affect their loneliness and well-being.