Malle has conjectured the order of growth of the number of field extensions with Galois group G of bounded discriminant, but he did not provide a conjecture for the leading constant. In this talk I will discuss joint work with Loughran where we give a prediction for the leading constant in Malles conjecture in analogy with Peyres constant for Manins conjecture, based on the analogy that Malles conjecture is Manins conjecture for the stack BG.