Fragility curves are developed for stone masonry buildings with rigid or flexible floors and varying number of storeys, plan dimensions, number of interior cross-walls, storey height, percentage of side length of exterior walls taken up by openings and wall height-to-thickness ratio. Linear Finite Element analysis in 3D is performed and a nonlinear biaxial failure criterion for masonry is used. Buildings with rigid floors and higher percentage of load-bearing walls are less vulnerable. Larger openings, taller storeys, larger number of storeys, higher wall slenderness and higher ratio of clear height to the horizontal dimension of the walls increase the vulnerability.