Does polystyrene float?
Does polystyrene float?
No
1,050 kg/m³ against water's 1,000
Polystyrene sinks. At 1,050 kg/m³ it is 1.05 times denser than water.
Why
Floating is decided by density alone — mass divided by volume — compared against the fluid. Weight has nothing to do with it directly: a 200-tonne ship floats and a 2-gram pebble sinks, because the ship encloses enough air to bring its average density below that of water. That is also the only reason a steel hull works.
The numbers
- Density
- 1,050 kg/m³ (1,040–1,060)
- Relative to fresh water
- 1.050×
- Floats in fresh water
- No
- Floats in seawater
- No
Compared with other materials
| Material | Density | Floats |
|---|---|---|
| pine | 500 kg/m³ | Yes |
| Douglas fir | 530 kg/m³ | Yes |
| mahogany | 590 kg/m³ | Yes |
| plywood | 600 kg/m³ | Yes |
| black walnut | 610 kg/m³ | Yes |
| OSB | 640 kg/m³ | Yes |
| particleboard | 650 kg/m³ | Yes |
| teak | 655 kg/m³ | Yes |
| ash | 675 kg/m³ | Yes |
| birch | 690 kg/m³ | Yes |
Common questions
- Does polystyrene float in water?
- No — at 1,050 kg/m³ it is denser than water's 1,000.
- Does weight decide whether something floats?
- No, density does. A 200-tonne ship floats and a small pebble sinks, because the ship encloses enough air to bring its average density below water.
Related pages
- Polystyrene properties Density, melting point, strength
- Does air float? Yes
- Does expanded polystyrene foam float? Yes
- Does rigid polyurethane foam float? Yes
- Does EVA foam float? Yes
- Does balsa float? Yes
- Does corrugated cardboard float? Yes
- Does cork float? Yes
- Does western red cedar float? Yes
Sources
- Typical range compiled from manufacturer specifications — At One Place