What to Do When Your Memory Foam Mattress Corners Are Not Expanding?

This research is supported by you, our readers, through our independently chosen links, which earn us a commission with no extra cost to you. Learn More

Written by: Alex Savy
Read 3 minLast updated July 14, 2020

Memory Foam Mattress Corners Are Not Expanding

These days, shopping for a new mattress is quite convenient, especially with so many bed-in-a-box options.

However, receiving a mattress compressed in a box can have its drawbacks, one of them being an improper expansion.

So, if your memory foam mattress corners are not expanding, read this guide to find out how to fix that issue.

Why Isn’t My Memory Foam Mattress Expanding?

When your new mattress doesn’t expand properly, there can be various reasons behind it, including the following:

  • You left it in the box for too long. Usually, manufacturers recommend users to unpack their new mattresses within the first 72 hours. Leaving your mattress compressed for too long can cause expansion issues.
  • It needs more time. Typically, memory foam takes up to 72 hours to expand fully (1). Therefore, if it’s only been a few hours after you’ve unpacked the mattress, don’t rush. The corners might expand later.
  • It’s too dense (or too thick). Thicker mattresses usually take longer to expand. The same rule applies to the ones using denser foam.
  • Your room is too cold. The visco-elastic chemicals in memory foam are temperature-sensitive. They become more fluid when the heat is applied. This means, leaving your mattress in a cool room will make it expand slower.
  • Your mattress is defective. Sadly enough, some memory foam mattresses (especially cheap ones) often arrive defective. They can be lumpy or have flat edges and corners that don’t expand even after a few days.

What to Do When Your Mattress Corners Don’t Expand

Here’s the deal:

Even if your new mattress doesn’t expand properly, some steps may help you fix the issue. Here’s what you can try:

  • Put it on the floor. If your bed frame isn’t suitable for a memory foam mattress, this may cause uneven expansion. Try putting the mattress on the floor and give it a bit more time to expand.
  • Return your mattress. If your mattress doesn’t expand fully within the first week, chances are it’s defective. In this case, the best solution would be to return it and pick a better quality model (which you can find here, among the best memory foam mattresses). Consider Nectar if you are looking for a good value for money. This mattress uses quality components and offers a universally comfortable medium feel.
  • Warm the room up. Warmth encourages memory foam expansion. Therefore, you can change your thermostat settings to at least 68 degrees Fahrenheit (or more) to help your mattress corners expand.
  • Massage the mattress. No matter how ridiculous it may sound, giving your mattress a massage by rolling on top of it may help. You can also walk on it for around 10-20 minutes (but make sure that your feet are clean).
  • Open the windows. Promoting air circulation can help your mattress expand fully (2). You can open the windows and create a draft in the room, which may also help with off-gassing. Placing a fan near the mattress is another option you can try.


There’s nothing more annoying than flat corners in your new memory foam mattress.

Of course, there’s a chance to fix the problem. Give your new mattress a bit more time or try a few tricks from the list above. 

Keep in mind that in some cases, returning the bed can be a better option. Higher quality mattresses are less likely to have issues with expansion and can guarantee your peace of mind.

What do you think? Will you try to fix your mattress? Or are you ready to exchange it for a better one? Let us know in the comments!


  1. Gail Delaney (2017, July 18). How to Expand Memory Foam. Retrieved from https://www.hunker.com/13403445/how-to-expand-memory-foam
  2. Emma Williams (2019, October 18). Can You Sleep on Memory Foam Before 24 Hours? Retrieved from https://www.alaskasleep.com/blog/what-if-you-sleep-on-memory-foam-before-24-hours

Leave a comment