So you’ve just bought a new memory foam mattress in a box and after removing the packaging exactly as the instructions describe, you’re now looking at a memory foam mattress that’s not expanded to its full size.
To fix a memory foam mattress that’s not expanding, put the mattress on the floor and wait 72 hours, increase the room temperature to 20°C (68 °F) or more, massage the mattress by rolling on it slowly for 10 – 30 minutes, and sleep on the mattress for a week – return the mattress if there’s no improvement.
The rest of this article explains how to make your memory foam mattress expand fully in 5 steps in more detail.
Alternatively: if your memory foam mattress is beyond repair, then check out my list of the best mattresses to buy online in 2021 here for a high-quality replacement.
How to Make a Memory Foam Mattress Expand
The main reason why compressed ‘bed in a box’ memory foam mattresses don’t expand fully after unboxing is due to foam pockets.
If you watch the video below, you can see for yourself how mattresses are compressed, folded, and rolled – allowing them to be put inside the neat little box that arrived at your door.
Foam pockets happen due to the mattress being cramped inside the box.
This is one of the dangers of leaving your memory foam mattress in the box for too long (which can sometimes void the warranty too).
However, the good news is that these foam pockets can often be removed by following the steps below.
And you don’t need to buy anything extra either.
But you MUST check the warranty or return policy FIRST to ensure that you’re not voiding it by following the steps below – and if you are, then you might be better off just going straight to step 5 to ensure that you don’t end up out of pocket.
Otherwise, follow the steps in the order below.
You can also combine some of the steps to save time.
1: Put the Mattress On the Floor and Wait 72 Hours
Time is often the most effective solution here.
Most modern memory foam mattresses are designed to expand fully in just a few hours so that you can sleep on them the same night.
However, you’ll find that many brands will say that it can take up to 72 hours for complete expansion.
Now, if you’ve already tried this then you might have some better luck if you move the mattress on to a hard surface like the floor because this can encourage expansion.
If you’ve yet to wait 72 hours and you have nowhere else to sleep then you should be fine sleeping on it on the first night (as long as this doesn’t void the warranty/return policy) – this can actually help expansion in many cases as described in step 4.
2: Warm the Room Up to at Least 20°C (68 °F)
You can do this at the same time as step 1.
Memory foam is temperature sensitive.
Cold inhibits expansion whilst warmth encourages it.
So if your room is cold, then you should heat it up until you’ve hit the average room temperature of 20°C (68 °F) – or slightly more.
If the mattress still hasn’t expanded fully after 72 hours using the temperature and floor technique then move on to step 3.
3: Roll On the Mattress For 10 – 30 Minutes
In addition to heat, movement can help to loosen memory foam up which can encourage inflation.
If you roll around on the mattress for between 10 and 30 minutes you may find that the memory foam starts to soften – allowing the mattress to expand fully.
You may find it more effective to just switch between various sleeping positions – holding each position for 5 – 10 minutes to allow the foam enough time to become warm and adjust to your body shape.
This technique alone can help fix your memory foam mattress if the middle or corners are deflated.
But I advise against standing on the bed because this type of concentrated pressure may negatively affect the memory foam – possibly leading to indentations or damage to the support core.
4: Sleep On the Mattress For a Week
If you’ve seen some minor improvement (or even none at all) after step 3, then sleeping on the mattress for a few days or a week might do the trick.
Because by spending a full night on the mattress, you’re allowing it to adjust to your body heat and weight for a prolonged period which may encourage full expansion.
It can take memory foam mattresses up to a month or more under normal conditions to begin to feel comfortable as it conforms to your sleeping style.
At this point, you may no longer care that your mattress isn’t fully expanded and you are comfortable sleeping on it.
5: Return the Mattress
If you’ve tried everything and your mattress still won’t expand – then you may have a defective mattress.
In which case, you should check the warranty – since many manufacturers list inflation issues as being a valid reason for a replacement.
Some manufacturers also provide a sleep trial – often up to 100 nights or more – to ensure that your mattress is right for you.
In which case, you should be able to return the mattress having opened it and slept on it.
Alternatively, some retailers have no-hassle return policies that you can take advantage of – just make sure that you’ve not gone over the time limit or breached any of the other terms.
I think I’ve covered most of the main points.
But if you have any extra questions, see the answers below.
Or leave me a comment at the end of the post and I’ll do my best to help you.
How Long Does it Take a Memory Foam Mattress to Expand?
Memory foam mattresses that come compressed in a box differ in their expansion times relative to each manufacturer.
Some brands claim that their mattresses will expand fully in 1 or 2 hours – whilst others may require a full day or more.
However, in nearly all cases, you’ll find that it shouldn’t take any longer than 72 hours for your memory foam mattress to expand fully.
If you’ve waited more than 72 hours, then there’s something wrong and you should follow the 5 steps above to try and get your memory foam mattress to inflate fully or return it.
Will Sleeping On a Memory Foam Mattress the First Night Inhibit Expansion?
Sleeping on your new memory foam mattress the first night shouldn’t damage it or inhibit expansion if you’ve allowed a few hours from the time of unboxing.
On the contrary, exposure to your body heat and weight may help to break the mattress in.
However, if the manufacturer says that you shouldn’t sleep on your memory foam mattress the first night – or within a certain time period – then I’d advise sticking to the rules so that you don’t risk damage and/or end up voiding the warranty.
That’s why I said earlier that you should check the warranty/return policy BEFORE following the steps above.
Are Cheaper Memory Foam Mattresses More Likely to Not Inflate?
I can’t say for sure that buying a more expensive or ‘high end’ memory foam mattress is a suitable way to avoid running into expansion issues.
However, cheaper memory foams may be lower in quality and potentially more easily damaged when held in a state of compression inside the vacuum-sealed packaging for too long.
Memory foam mattresses that include very low-density foams of 3 pounds per cubic foot or lower may be more likely to encounter expansion issues when left compressed for too long – but this is not an absolute rule by any means.
Protect Yourself With a Sleep Trial
If you’ve yet to buy a memory foam mattress then I would suggest looking for one with a sleep trial of up to 100 nights and a good warranty that covers inflation issues even after you’ve opened and slept on the mattress.
This way, you can be sure that you can sleep on the mattress without running into problems when you need to return the mattress – such as ‘hygiene reasons’.
But if you’ve already bought the mattress and you’re having inflation issues, then the application of time, heat, and movement as described in the 5 steps above are your best solutions.
If that doesn’t work – you should try to return the mattress and get a refund or a replacement through the manufacturer or the retailer.
Click the button below to see the best mattresses with the longest sleep trials to buy now.
Image Attribution and Licencing
Main image: ‘Elegant Bedroom’ by ArchIdeaPhoto (Getty Images) – used with permission under the terms of Canva’s One Design Use License Agreement.
Dan is the founder and head content creator at Bedroom Style Reviews.
He has been working as a professional online product reviewer since 2015 and was inspired to start this website when he ended up sleeping on a memory foam mattress that was too soft and gave him backache.
Through in-depth research and analysis, Dan’s goal with this website is to help others avoid such pitfalls by creating the best online resource for helping you find your ideal mattress, bedding, and bedroom furniture.
Dan is a qualified NVQ Level 2 Fitness Instructor with 6 years’ experience helping clients improve their health through diet, exercise, and proper sleep hygiene.
He also holds several college and university-level qualifications in health sciences, psychology, mathematics, art, and digital media creation – which helps him to publish well researched and informative product reviews as well as articles on sleep, health, wellbeing, and home decor.
Dan also has direct personal experience with insomnia, anxiety, misophonia (hypersensitivity to sounds), and pain from both acute and long-standing sporting injuries – he enjoys writing insightful articles around these subjects to help fellow sufferers of such conditions.
Learn more about Dan here.