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Foam density is the mass of foam per unit volume. In the UK it is measured in kilograms per cubic metre (kg/m³); in the US it is measured in pounds per cubic foot (PCF). It is a crucial factor in the design and manufacture of custom cushions, as it significantly affects their comfort, durability and performance.
Understanding foam density helps anyone designing, making or buying custom cushions to choose the right foam and know what performance and comfort to expect. This guide explains what foam density is, how it is measured, typical densities for common foams, and how density affects cushions.
Figures are indicative only. The actual density of a specific foam depends on its formulation and manufacturing process.
| Foam Type | Typical Density (kg/m³) | Typical Density (PCF) | Common Uses |
|---|---|---|---|
| Polyurethane foam | 29 to 40 | 1.8 to 2.5 | Furniture cushions |
| High-resilience (HR) foam | 40 to 48 or more | 2.5 to 3.0 or more | High-end furniture and mattresses |
| Memory foam | 48 to 80 | 3 to 5 | Mattresses and pillows |
Foam density measures how much material is packed into a given volume of foam. A higher-density foam has more material in the same volume, so it is heavier and generally more durable. A lower-density foam has less material, so it is lighter. Density is not the same as firmness: a high-density foam can be soft and a low-density foam can be firm, as firmness is a separate property.
Density is determined by the raw materials used, the manufacturing process and the structure of the foam. Different types of foam have different densities, and even within the same type there can be significant variation.
Foam density is measured by finding the mass and volume of a foam sample. The sample is weighed on a scale, its dimensions are measured to calculate its volume, and the mass is divided by the volume. In the UK the standard method is BS EN ISO 845, which gives a result in kg/m³ (1 PCF is about 16 kg/m³).
The density can vary within a single piece of foam, especially a large one. Taking measurements at several locations and averaging them gives a more accurate figure that represents the whole piece, not just a small section. See our guide to foam testing.
Each type of foam has its own typical density range:
These are typical ranges only. The actual density of a specific foam depends on its formulation and manufacturing process, so when choosing foam for a custom cushion, check the specific density of the foam you are considering, not just the typical range for its type.
The density of the foam in a custom cushion has significant implications for its performance, comfort and durability. Higher-density foams tend to be more durable and hold their support for longer, but they are also heavier. Lower-density foams are lighter, but may not be as durable or supportive. Choosing the right density means balancing these factors.
Comfort is a key consideration. Higher-density foams tend to keep their support better, which can help prevent discomfort for people who sit or lie on a cushion for long periods. Lower-density foams can give a plush feel, but may not provide as much support over time. Because density and firmness are separate, the feel of a cushion also depends on the foam’s firmness, so consider both together. See our guide to foam compression.
The performance of a custom cushion, in terms of comfort, support and responsiveness, is significantly influenced by foam density. Higher-density foams tend to retain their shape and support better over time, helping the cushion perform well for longer.
Lower-density foams tend to lose their shape and support more quickly, which can lead to a decline in performance, particularly for people who need a higher level of support. They can still be very comfortable, especially for people who prefer a softer, more plush feel.
Durability, the ability to withstand wear and tear and keep its shape and support over time, is also strongly influenced by density. Higher-density foams are more resistant to permanent compression and deformation, so they can withstand more use without losing their shape, extending the cushion’s lifespan.
Lower-density foams are more susceptible to compression and deformation, so they can lose their shape more quickly with use, shortening the cushion’s lifespan. With proper care and maintenance, however, even lower-density foams can give a reasonable lifespan.
Several factors influence foam density:
Understanding these factors helps you choose the right foam for a custom cushion and know what performance and comfort to expect.
Foam density plays a crucial role in the design and manufacture of custom cushions. It affects their comfort, performance and durability, and depends on the raw materials, manufacturing process and structure of the foam. Understanding it helps you choose or create custom cushions that meet your specific needs and preferences.
Continue exploring how foam properties affect your cushions across our glossary:
The Foam & Covers team can help you choose a foam density and firmness to suit how your cushions will be used, and cut it to your exact measurements.
Contact Our Foam Specialists or Order Custom Cut Foam Online .
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