Embodiments described herein provide systems and methods for minimizing deceleration of downhole tools when the downhole tools are pumped down into wellbores through drill pipe in an untethered manner. For example, embodiments described herein include a hydraulic downhole tool deceleration system that includes a hydraulic decelerator configured to be affixed to a downhole tool string pumped down through drill pipe during operation. The hydraulic decelerator is configured to contact a hard shoulder while traveling through the drill pipe, and to limit an initial magnitude of deceleration of the downhole tool string caused at the initial moment of contact of the hydraulic decelerator against the hard shoulder.