The dispensing volume or dosage of a screw lotion pump is determined by several key factors, which include:

Pump Design and Mechanism: The design of the pump and its internal mechanism play a significant role. Some pumps are designed to dispense a fixed amount per pump while others might have an adjustable mechanism to control the amount dispensed.

Piston or Diaphragm Size: The size of the piston or diaphragm within the pump affects the amount of product displaced or pushed out with each pump action.

Thread Pitch or Pitch Diameter: The thread pitch or pitch diameter of the pump's mechanism influences the amount of product delivered per rotation or pump action.

Stroke Length: The distance the pump head or piston travels inside the pump during operation affects the volume dispensed with each stroke.

Nozzle Size and Opening: The diameter and design of the nozzle impact the flow rate of the dispensed product. Larger nozzle openings can allow for higher volumes to be dispensed per pump.

Viscosity of the Product: The thickness or viscosity of the liquid being dispensed affects how easily it flows through the pump mechanism. Thicker products might be dispensed in smaller volumes due to the resistance within the pump.

Pump Adjustability: Some screw lotion pumps come with adjustable features that allow users to control or customize the dispensing volume. These adjustments may include settings to regulate the amount dispensed with each pump or stroke.

Pressure Applied: The pressure exerted on the pump by the user’s action determines the amount of product dispensed. Harder or softer pressing may affect the volume dispensed.

User Preferences and Experience: Different users may have varying preferences for the amount of product dispensed, and manufacturers often cater to these preferences when designing the pump's dispensing volume.

Considering these factors, manufacturers design screw lotion pumps to dispense a particular volume or dosage, and users can sometimes adjust this volume based on the pump's design o