We investigated associations between online and offline socialising and groups of social ties as postulated by the Social Brain Hypothesis (SBH). An online survey of social media use, social satisfaction and loneliness generated 249 complete responses from a sample of staff and students at the University of Manchester. Regression-based analyses showed that offline social activities and social time were positively associated with size of a core support group and social satisfaction. In contrast, social media time was positively associated with social satisfaction and the size of the total network, while the number of online contacts was positively related to social satisfaction, size of a wider sympathy group and total network size. No effect for loneliness was found. The number of ties reported for each SBH group was similar to that in previous studies. The more intimate support group (∼5) appears to be more closely connected with offline social activities, whereas social media use and contacts influence the less intimate sympathy group (∼15) and total network (∼150). These findings provide further support for functional differences between different layers of closeness in personal networks, and they help us in further defining the boundaries of relationship enhancement via communication technology.