ABSTRACT Planets and planet candidates are subjected to great investigation in recent years. In this study, we analyse 20 planet and planet-candidate host stars at different evolutionary phases. We construct stellar interior models of the host stars with the mesa e.volution code and obtain their fundamental parameters under influence of observational asteroseismic and non-asteroseismic constraints. Model mass range of the host stars is 0.74–1.55 $\rm M_{⊙ }$. The mean value of the so-called large separation between oscillation frequencies and its variation about the minima shows the diagnostic potential of asteroseismic properties. Comparison of variations of model and observed large separations versus the oscillation frequencies leads to inference of fundamental parameters of the host stars. Using these parameters, we revise orbital and fundamental parameters of 34 planets and four planet candidates. According to our findings, radius range of the planets is 0.35–16.50 $\rm R_{{⊕ }}$. The maximum difference between the transit and revised radii occurs for Kepler-444b-f is about 25 per cent.