The concepts of potential growth and output gap are important tools to evaluate the state of the business cycle and to assess the supply-side capacity of an economy. They have also become an essential ingredient of the European fiscal surveillance process. However, the global economy is facing its most widespread crisis in the post-war era and consequently the uncertainty regarding the impact of the crisis on supply-side conditions is enormous.  In this Working Paper we compare revisions on potential growth for Belgium made recently by the Federal Planning Bureau and international organizations. Those comparisons aim at highlighting the uncertainty associated with those revisions as well as understanding better some of the channels through which the crisis may reduce potential output.