Handheld electromechanical surgical system

A surgical device comprising: a handle assembly (100) including: a power source (144); at least one motor (153) coupled to the power source; and a controller (143) configured to control the motor; an adapter assembly (200) configured to selectively couple to the handle assembly, the adapter assembly including a strain gauge (320) configured to measure strain; a reload (400) configured to selectively couple to a distal portion of the adapter assembly, the reload including: a plurality of fasteners ("S"); an annular staple pusher (434) for ejecting the plurality of staples; and an anvil assembly (510) selectively couplable to the distal portion of the adapter assembly, the anvil assembly being movable relative to the reload; wherein the controller (143) is configured to control the motor (153) to move the annular staple pusher (434) based on the measured strain.