Theoretical prediction of complete p-y curves applicable to the design of laterally loaded piles in clay is presented. In common pile terminology, the p-y curve represents the pressure-displacement relationship applicable to a pile segment during lateral displacement. The p-y curve was characterised by initial stiffness (Ki), displacement to the limit of linear elastic behaviour (ye), displacement required to reach ultimate pressure (yu) and the ultimate pressure (pu). On the basis of a numerical parametric study using FLAC program, relationships between governing non-dimensional quantities involving the above parameters were developed in graphical and closed forms. These relationships identified the importance of accounting for the likelihood of pile-soil tension failure during pile displacement. Non-dimensional design charts were produced catering for the cases of both tension failure and no tension failure. These charts with the parametric relations developed can be used to establish theoretically the p-y curves applicable to pile sections that are free from the influence of the ground surface.