Laboratory experiments to estimate solitary wave runup were performed on three different planar beaches with slopes of 1/4, 1/7 and 1/10, with varying wave heights and water depths. The non-dimensionalised vertical runup (runup over water depth) obtained from present laboratory data and several published sources were plotted against the surf similarity parameter. Best-fitting curves could be obtained for maximum runup on slopes ranging from 1/1 to 1/60 against the surf similarity parameter. Hence an approximate formula is presented for estimation of maximum solitary wave runup on planar beaches of different slopes regardless of whether the waves are breaking or non-breaking. The proposed empirical equation predicts the overall dataset, mostly within 20% scatter for all the laboratory data. Thus, the empirical formula can be used to obtain a quick estimation of maximum runup height for both breaking and non-breaking solitary waves in laboratory experiments, for disaster risk evaluation of wave runups and to verify numerical model runup results.