Quick answer: Open-cell foam contains interconnected cells that let air move through the material; closed-cell foam has more enclosed cells. Those labels describe structure, not a single feel or use. Flexible open-cell polyurethane foam is common in mattresses, while both open- and closed-cell spray foams are used in building insulation.
Properties depend on the particular formulation, density, thickness and construction. A mattress comfort layer should not be treated as interchangeable with spray foam used in walls.
Open-cell vs. closed-cell foam
| Characteristic | Open-cell | Closed-cell |
|---|---|---|
| Cell structure | Cells are interconnected to varying degrees. | More cells are enclosed rather than connected. |
| Air and moisture | Often permits more air and moisture movement. | Often resists air or water movement more, but resistance varies by material and installation. |
| Feel | Can be flexible or firm depending on formulation. | Can be flexible, as in some camping pads, or rigid, as in some insulation products. |
| Examples | Flexible upholstery and mattress foam; some spray insulation. | Some camping pads, packaging and spray insulation. |
Neither type is automatically waterproof, mold-proof, soundproof or comfortable for every purpose. Test data and the conditions of use matter.
Which foam is used in mattresses?
The Polyurethane Foam Association describes flexible polyurethane foam as an open-cell material, and its bedding guide notes that manufacturers use flexible foam in mattress cores and comfort layers. Memory foam is a viscoelastic type of flexible polyurethane foam; different formulations recover and contour differently.
Open cells do not guarantee a mattress sleeps cool. The cover, foam density and thickness, other layers, bedding and room conditions all affect temperature. A “cooling” label is not the same as active cooling, and a foam layer can be soft or firm regardless of its cell label.
When comparing a mattress or topper, ask about firmness, layer thickness, feel, care, return terms and any relevant certification. CertiPUR-US certification applies to eligible polyurethane foam, not automatically to the complete mattress.
For a broader explanation of mattress construction, see our hybrid mattress guide or zoned coil guide.
What about spray-foam home insulation?
Open- and closed-cell spray polyurethane foams are separate product categories with different thermal and moisture properties. A U.S. Department of Energy building guide discusses typical values of roughly R-3.5 per inch for open-cell and R-6 per inch for closed-cell spray foam. These are illustrative values for spray insulation, not ratings for mattress foam; the actual product and installed thickness determine performance.
Moisture management depends on the assembly, climate and product. Closed-cell spray foam is not automatically a complete vapor barrier at every thickness, and neither foam eliminates the need to address leaks, condensation or building design. For an insulation project, use the manufacturer’s current technical data and a qualified installer familiar with local requirements.
Sound absorption and blocking sound transmission are also different. Do not assume either spray foam will soundproof a room; walls, gaps, mass and construction details affect the result.
How to choose the right product
- Define the application. A mattress topper, backpacking pad and wall insulation require different specifications and safety instructions.
- Check the actual performance data. For insulation, review R-value, thickness and moisture properties; for a sleeping pad, look at the tested pad R-value and trip conditions.
- Check fit and feel. For bedding, consider pressure relief, support, heat sensation, dimensions and trial conditions.
- Read care and safety instructions. Check washability, flammability information and any warnings for the specific finished product.
- Compare the complete setup. A single layer or material label does not describe the whole mattress, wall assembly or camping sleep system.
For an example of a closed-cell sleeping pad, our Big Agnes pad comparison covers the TwisterCane and its manufacturer-listed R-value.
Frequently asked questions
Is open-cell foam always soft?
No. Flexible foams can be formulated with different firmness levels, and open-cell building insulation is a different product from bedding foam.
Is closed-cell foam always rigid?
No. Some closed-cell foams are flexible, including certain camping and exercise pads.
Is closed-cell foam waterproof?
It can resist moisture, but waterproofness depends on the product, thickness, seams and exposure. Check manufacturer data for the intended use.
Does open-cell mattress foam guarantee cooler sleep?
No. Air movement is one factor; the complete mattress and bedding influence temperature.
Can I use spray-foam R-values to compare mattresses?
No. Those numbers describe particular building insulation products and should not be applied to mattress comfort layers.
Final take: Start with the intended application and the specific product’s tested properties; the cell label alone is not enough to choose.
Compare both beds against 142 tested mattresses
Sort all 142 mattresses we have tested by pressure relief, support, cooling, motion isolation, edge support, price, trial and warranty, then filter by how you actually sleep. Of those, 84 hold a complete standardized record and 41 a partial standardized record.