Field adjustable piston actuators are described. An example field adjustable piston actuator includes a housing having opposing openings and a chamber. Additionally, the example piston actuator includes a first plate coupled to the housing and adjacent one of the opposing openings. Further, the example piston actuator includes a second plate coupled to a yoke and the housing. The second plate is adjacent the other one of the opposing openings. Further still, the piston actuator includes a volume adjuster to provide field adjustment to change a volume of the chamber.