Why Is My Memory Foam Mattress Not Expanding | Best Know

You’ve just purchased a new memory foam mattress, and you’re excited to experience the comfort it promises. But you’ve seen that it’s not expanding as expected. We understand how annoying this can be when you’re looking forward to a good night’s sleep.

Usually, new mattresses take 24 to 72 hours to expand. Sometimes, memory foam mattresses take a long time to expand for various reasons.
Our expert team found 5 of the most common reasons memory foam mattresses do not expand.

So, we are sharing vast research and analyzing detailed information about memory foam mattresses. It will help you understand why your foam mattress might not expand and how to make it grow fast.
Let’s go to start.

5 Reasons Why Your Memory Foam Mattress Is Not Expanding

There are many reasons why your memory foam mattress might not be expanding as it should.

Memory foam requires warmth to expand fully. Placing the mattress in a more excellent space can impede expansion. To get the best results, put the bed at 70-75 degrees Fahrenheit or 21-24 degrees Celsius. Here are the top five reasons for memory foam mattresses not expanding.

Memory Foam Mattress Is Not Expanding

Reason 1: You haven’t given it enough time

Memory foam mattresses need time to expand and regain their original shape. Think of it like a sponge that needs time to absorb water and puff up. Most memory foam mattresses require at least 24 to 48 hours to reach their full size. You should be patient if you open the box and think it will immediately become a cloud-like bed.

Reason 2: Your room may be too humid

Humidity can be a real buzzkill for your mattress expansion plans. Excess moisture in the air can slow down the expansion process. In the same way, it’s harder to dry off with a wet towel; a humid room can make it hard for your mattress to spread fully. Use a dehumidifier to lower the room’s wetness and help your mattress dry out faster.

Reason 3: Your room is too cold

Temperature matters when it comes to memory foam mattresses. Cold rooms can make the foam feel firmer and less responsive. It’s like trying to bend a complex piece of chocolate; it won’t be as pliable as a warm one. Ensure your room is comfortably warm, and the mattress will quickly expand.

Reason 4: Your mattress is too dense

Not every memory foam mattress is the same. Some are more thick than others, which can slow or speed up how fast they grow.

Because it has more decompressible material, a larger mattress may take longer to expand to its full size.

Reason 5: Your mattress is defective

In rare cases, your mattress might have a manufacturing flaw that keeps it from growing correctly.

If you’ve tried everything and it won’t blow up, it’s time to contact the maker or the seller. They can figure out what’s wrong and get a repair if needed.

Your memory foam mattress may not expand due to various factors. Many things can cause this, such as insufficient time, high humidity, low room temperature, and a dense bed.

How Can I Make My Memory Foam Mattress Expand Faster?

If you’ve been waiting for your memory foam mattress to grow fast, but it is taking time, don’t worry. There are practical steps you can take to speed up the process and enjoy your cozy bed sooner. Let’s get right to these five ideas without any filler.

How Can I Make My Memory Foam Mattress Expand Faster

1. Place the memory foam in a warm room

Memory foam requires heat to activate and expand. Place your mattress in a warm room, ideally between 70 to 78 degrees Fahrenheit or 21 to 26 degrees Celsius. The higher the temperature, the faster the foam will expand. Use a space heater to warm the room. Do not overheat the mattress, as this could damage the materials.

2. Apply Direct Heat

You can heat the mattress with an electric blanket, heating pad, or hair dryer. Make sure the heat source is 6 inches or 15 centimeters away from the bed. Keep moving it to avoid overheating any areas. Only do this for 10 to 15 minutes at a time, with breaks between, to allow the heat to distribute within the mattress.

3. Wait 72 hours

The expansion process can take up to 72 hours to complete. Be patient and avoid sleeping on or compressing the mattress during this time. Expect the mattress to increase to its full, advertised height. The comers and edges, in particular, can take the longest to fill out.

4. Walk or roll on the mattress

After the mattress has expanded for 24 hours, you can walk or crawl on it to loosen the foam and make it expand faster in compressed areas. Do this for just 10 to 15 minutes at a time, a few times per day. When the foam is moved and compressed, it will expand more when released.

 5. Adjust To Room Temperature

Memory foam responds to temperature and can stretch out better when it’s warmer. If your room is too cold, it’s easier to move around, like trying to bend a stiff piece of plastic. Make sure your room is warm enough to be comfortable. It will help your mattress relax and spread.

6. Separate The Mattress Layers

Some memory foam mattresses come with many layers, like a sandwich. If these layers are stuck together, they can’t expand correctly. Separate them so that each layer can breathe and fluff up independently.

Watch out for any zippers or other fixings that hold the pieces together. If there are any, remove them by following the maker’s directions.

7. Improve Air Circulation

Air is like magic for your mattress. It helps it puff up and become super soft. You can aid this process by enhancing air circulation in your room. Here’s how:

  • Open windows to let in fresh air.
  • Use fans to keep the air moving.
  • Allow for gentle breezes to flow through your room.

The more air circulates your mattress, the faster it will expand.

Memory Foam Mattress Corners Not Expanding

If your memory foam mattress corners are not expanding, there could be a few reasons.

1. Temperature

Memory foam relies on body heat to soften and conform to your shape. If the room temperature is too cool, the memory foam will remain firm, and the corners may be the last to ease. Ensure the room is at least 65 to 72 degrees Fahrenheit for optimal memory foam pliability. To help the memory foam expand, you can use an electric blanket, heating pad, or mattress topper. These will provide direct warmth to the corners.

2. Time

Memory foam can take up to 72 hours to expand after unpacking. The corners are the last area to fill out as they receive less direct pressure and warmth. Be patient during the initial expansion period. To help the memory foam activate faster, you can walk or roll on the mattress.

3. Positioning

The position of the mattress on the base can impact the expansion of the corners. Ensure the bed is centered on the foundation. If the bed is not aligned on the ground, the corners may bulge or not fill in fully. Re-position the mattress so it lies flat and even for the best results.

4. Mattress Layers

If your memory foam mattress has many layers, they might have shifted during shipping. To help the memory foam expand, massage and roll the corners to align the layers. Flipping or rotating the entire mattress may also help in some cases.

Be patient, as it can take up to 3 days for a memory foam mattress to reach most size and flexibility.

How Long Does It Take for the Corners of a Memory Foam Mattress to Expand?

It can take up to 72 hours for the corners of a new memory foam mattress to expand. Memory foam needs time to adjust to room temperature to soften and contour properly. The corners are often the last area of the bed to expand.

There are a few reasons why memory foam mattress corners may take longer to expand:

1. Memory foam reacts to body heat and pressure to mold to your shape. The mattress corners are exposed to air, so they take longer to reach the ideal temperature. This temperature allows the foam cells to soften and expand. Placing the bed in a warm room and using an electric blanket or heating pad can help speed up expansion.

2. The corners have less surface area in contact with your body, so they receive less heat and pressure. Using a fan to improve airflow can help the foam on the mattress reach the right temperature. Separating the mattress layers or flipping and rotating the bed can also help.

3. Memory foam mattresses often have many layers of foam for support and comfort. The center layers of the mattress expand first. The foam in the corners takes longer to soften and spread out. Separating and rearranging the layers can speed up expansion in the corners.

4. Larger beds, such as king and California king sizes, need more foam to expand. It can take 3 to 5 days for them to grow fully. Be patient during the break-in period. To help the mattress expand faster, walk or roll on it, especially in the corners.

Your memory foam mattress will stay at a comfortable temperature, providing excellent support and comfort. You need the initial expansion period for your new mattress to get all the benefits. Have patience- your memory foam mattress corners will soften and expand in time.


Our vast research will help make memory foam mattresses very comfortable and supportive. Our helpful information and tips can help your memory foam mattress expand faster.

So, following the tips mentioned above, you can ensure that your memory foam mattress expands as expected. Remember that patience is vital in this process. Allow your mattress the time it needs to provide you with the best sleep experience.

Let us know if you have any advice or questions about the memory foam mattress.

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