We investigate fracture in a monolayer graphene with a small concentration of vacancies, using molecular dynamics. The samples consist of layers of varying size, encompassing more than three decades; we systematically study the mechanical failure following simulated “constant engineering strain” conditions. We compute the fracture strength distribution as a function of system size and defect concentration; the data show evidence of complex size effects and scaling laws. We compare the results with extreme value statistics and we propose a simple model that appears to be able to capture the main features of fragile fracture.