The density (specific gravity) of PS resin is an industry-recognized standard physical parameter, divided into two main categories—GPPS and HIPS—with stable base density values tested in accordance with international standards such as ASTM D792 and ISO 1183.

Density varies slightly across different grades and modified types of PS, with all values being industry-recognized measured data:

General-purpose GPPS (transparent polystyrene): 1.04～1.06 g/cm³, typical value 1.05 g/cm³

High-impact HIPS (modified polystyrene): 1.03～1.05 g/cm³, typical value 1.04 g/cm³, with slightly lower density due to rubber phase addition

Flame-retardant PS: 1.06～1.12 g/cm³, with halogen-free flame-retardant systems showing smaller density increases than halogenated systems

Inorganic-filled PS: 1.10～1.20 g/cm³, with higher filler ratios leading to greater density

Glass fiber-reinforced PS (10%～30% glass fiber): 1.15～1.30 g/cm³, with higher glass fiber content leading to greater density

This density parameter is a core reference for the design of transparent products, home appliance interiors, and packaging materials. Its moderate density, combined with good moldability, makes it widely used in thin-walled injection-molded products, and density calculation is also fundamental for product dimension design and production efficiency optimization.