Internationalisation is a major trend in higher education worldwide. Yet, little evidence is given on the net impact of international students on national economies. This study addresses this gap by estimating the benefits against the costs driven by international students in Belgium and its Flemish region in particular. Using a unique combination of various sources of micro-data, the results show net positive benefits that exceed costs by a factor ranging between 2.4 (lower bound) and 3.1 (upper bound) times. The results vary highly with the level of education, as the ratio is the lowest for doctoral students (1.2-1.6) and highest for master students (5.1-6.3). The effect is mainly driven by a high stay rate of international students, who are likely to work in the country after graduation. When considering indirect effects, our results show that there are no significant peer effects due to the presence of international students in the classroom.