This paper proposes a novel method for dimensioning pneumatic cylinders for motion tasks. Considered are standard pneumatic cylinders with common directional control valves and exhaust flow throttles. The focus thereby is on the dimensioning of the cylinders for point-to-point motions regarding energy efficiency. The proposed strategy is based on the eigenfrequency and considers similarity transformations. The dimensioning of the cylinder diameter and the valve conductance bases upon a few algebraic equations leading to optimally sized pneumatic cylinders. Furthermore, the equations are used for classification purposes of the pneumatic cylinders regarding energy efficiency.