According to Young's equation, the contact angle "theta" is considered as the measurable wettability parameter. The rate of change in the contact angle has been commonly used as the relevant parameter of spreading dynamics notwithstanding the difficulties associated with contact angle measurements that are well recognized in the literature. Considering that the velocity of the contact line is the pertinent quantity, it is, therefore, reasonable to regard the change in the contact area as the flux of the process. In this study, we have introduced a new measuring parameter for wettability based on the liquid/solid contact area. The term "contact ratio" has been coined to account for this new measurable parameter. The contact ratio is defined as the ratio between the spreading contact area of liquid over solid surface and the surface area of the spherical drop before spreading. The measurements of contact areas and low-rate dynamic contact angles for various liquid/solid systems were conducted independently using the ADSA-P technique. The theoretical relation between the contact ratio and the contact angle is derived based on spherical cap approximation. The results show that there is a good correlation between the theoretical relation and the experimental values. Since the contact angle of a specific system is a unique parameter of the system, the contact ratio can also be presented as a unique parameter of the system. Nevertheless, contact ratio presents a more precise measure of wettability.