This study explores the type and frequency of extramural English (EE) (e.g. reading, speaking and gaming) and relationships between EE activities and performance on a standardised English reading comprehension (ERC) test in a sample of young adults, with a particular focus on potential sex differences and online gaming as an EE activity. Participants consist of 6,079 test-takers of the Swedish Scholastic Aptitude Test (SweSAT), a test used for admission to higher education, which has ERC as one of the subtests and the only SweSAT subtest that assesses English proficiency. The type and frequency of engagement in EE activities were assessed through a self-report questionnaire. Correlation, ANOVA and multiple linear regression analyses were conducted to explore how EE activities influence ERC performance, as well as differences between males and females. Overall, the results show positive correlations and significant relationships between EE activities and ERC ability, especially reading, watching English content and moderate-to-high frequency of gaming. Sex differences in EE exposure and test performance were observed. In summary, results from this large-scale study corroborate previous findings that English language acquisition also takes place outside the formal context and that leisure-time activities may enhance ERC ability. Implications are discussed.