This article anatomizes the ‘productivity race’ between Nazi Germany and the US over the period from the Great Depression to the Second World War in the metalworking industry. We present novel data that allow us to account for both the quantity of installed machine tools and their technological type. Hitherto, comparison of productive technologies has been limited to case studies and well-worn narratives about US mass production and European-style flexible specialization. Our data show that the two countries in fact employed similar types of machines combined in different ratios. Furthermore, neither country was locked in a rigid technological paradigm. By 1945 Germany had converged on the US both in terms of capital-intensity and the specific technologies employed. Capital investment made a greater contribution to output growth in Germany, whereas US growth was capital-saving. Total factor productivity growth made a substantial contribution to the armaments boom in both countries. But it was US industry, spared the war's most disruptive effects, that was in a position to take fullest advantage of the opportunities for wartime productivity growth. This adds a new element to familiar explanations for Germany's rapid catch-up after 1945.