Abstract In this article, we investigate the position-access workspace estimation of slender soft manipulators controlled via arranged bounded actuators. For this, we implement a so-called forward-backward approach on the mathematical model of the investigated soft robot deduced via the adopted Discrete Cosserat method. The proposed methodology is validated on several planar and spatial slender soft manipulators’ configurations, where we show its advantage of reducing computation complexity for estimating the workspace, compared to traditional forward approach.