The present study aimed to analyze sex differences in arithmetical performance in a large-scale sample of 390 children (193 boys) frequenting grades 1-9. Past research in this field has focused primarily on average performance, implicitly assuming homogeneity of variance, for which support is scarce. This article examined sex differences in arithmetical operations (addition, subtraction, multiplication and division) in central tendency and variability. Central tendency analyses revealed a male advantage, predominantly in addition and subtraction, from grade 6 onward. Variability analyses showed that sex differences were largest among higher achievers and absent among lower achievers. Thus, central tendency and variability analyses provide complementary information on sex differences in arithmetical performance. In conclusion, sex differences in arithmetical performance exist, but depend on the studied arithmetical operation, age group and achievement level. The present study thereby offers new directions for future research by indicating the need for a broader perspective on sex differences.