How long does a memory foam mattress take to expand?

How long does a memory foam mattress take to expand?


Memory foam mattresses have become increasingly popular due to their ability to provide comfort and support during sleep. However, one common question that arises is how long it takes for a memory foam mattress to fully expand after being unpacked. In this article, we will explore the factors that influence the expansion time of a memory foam mattress and provide insights into what to expect during this process.

Factors Affecting Expansion Time

Materials used: Memory foam mattresses are made from viscoelastic polyurethane foam, which is highly responsive to temperature. The density and composition of the foam can affect how quickly it expands. Higher-density foams may take longer to fully expand compared to lower-density ones.

Thickness of the mattress: Thicker mattresses generally take longer to expand fully. This is because the thicker the mattress, the more foam there is to expand and regain its original shape.

Room temperature: Memory foam mattresses expand faster in warmer temperatures. If the room is colder, it may take longer for the mattress to reach its full expansion.

Compression during shipping: Memory foam mattresses are typically compressed and vacuum-sealed for shipping. The duration of compression can impact the expansion time. Mattresses that have been compressed for a longer period may take longer to fully expand.

Typical Expansion Time

The average memory foam mattress takes anywhere from 24 to 72 hours to fully expand. However, it’s important to note that this is just an estimate, and the actual time can vary depending on the factors mentioned above.

During the initial hours, you may notice that the mattress starts to expand and take shape. However, it may still feel uneven or have visible indentations. This is normal, and it can take some time for the foam to fully recover and regain its intended form.

What to Expect During the Expansion Process

In the first few hours after unpacking, the mattress will begin to expand as the foam cells decompress. You may notice a slight odor during this time, known as off-gassing. This is a normal occurrence and is caused by the release of volatile organic compounds (VOCs) trapped within the foam. The odor should dissipate within a few days, especially if the room is well-ventilated.

As the mattress expands, it may feel firmer than expected. This is because the foam needs time to fully recover its original shape and reach its intended level of softness. It is recommended to wait for the full expansion period before judging the comfort level of the mattress.


The time it takes for a memory foam mattress to expand fully can vary depending on several factors, including the materials used, thickness, room temperature, and compression during shipping. On average, it can take anywhere from 24 to 72 hours for a memory foam mattress to reach its full expansion. During this time, it is normal to experience off-gassing and a firmer feel. Patience is key, and it is advisable to wait for the full expansion period before evaluating the comfort and support provided by the mattress.