The BBC Loneliness Experiment provided a unique opportunity to examine differences in the experience of lonelines across cultures, age, and gender, and the interaction between these factors. Using those data, we analysed the frequency of loneliness reported by 46,054 participants aged 16–99 years, living across 237 countries, islands, and territories, representing the full range of individualism-collectivism cultures, as defined by Hofstede (1997). Findings showed that loneliness increased with individualism, decreased with age, and was greater in men than in women. We also found that age, gender, and culture interacted to predict loneliness, although those interactions did not qualify the main effects, and simply accentuated them. We found the most vulnerable to loneliness were younger men living in individualistic cultures. •Younger people reported more loneliness than the middle-aged.•The middle-aged reported more loneliness than older people.•Men reported more loneliness than women.•People in individualistic (vs. collectivist) countries reported more loneliness.•Age, gender, and culture interacted to predict loneliness.