6 mistakes everyone makes when setting up a bed in a box mattress

From using the wrong tools to not letting it expand properly, here’s what NOT to do when setting up a bed in a box mattress

A man pulling a bed in a box mattress out of a Casper box with a dog sat next to it
(Image credit: Casper)

When you buy a mattress online, it’s most likely going to arrive tightly rolled and vacuum-wrapped in plastic, inside a large cardboard box. This is what is called a bed in a box mattress. Investing in a bed in a box mattress means you’re getting a supportive and comfortable mattress for your sleep needs, and it’s more quickly and easily delivered to your door, ready for you to unbox in a moment’s notice.

Most mattress manufacturers will deliver their mattresses this way, including the likes of Simba, Emma, Casper and Nectar. Once your bed in a box mattress arrives, the unboxing and set-up is relatively simple, particularly as your brand of choice will provide you with in-depth instructions.

But before you start wielding your scissors, it’s important to know what you’re doing when setting up your bed in a box mattress. As someone who has tried some of the best mattresses on the market, most of which arrived in a box, I have made all the mistakes there are to make… and you’d be surprised how easy it is to make them!

To help you set up your new sleep surface, here are six mistakes everyone makes when setting up a bed in a box mattress, and how to avoid them.

1. Not getting the mattress delivered to your room of choice

When you order your bed in a box mattress, most delivery people will deliver it to your room of choice, and in some cases, will remove your old mattress at the same time. But if you forget or don’t want to select this option, you’ll be putting yourself through a bit of a struggle.

Take it from me – bed in a box mattresses are HEAVY. Regardless of the brand, type or size of mattress you pick, a tightly packed mattress in a big cardboard box is going to have some weight to it. So, if you can have the delivery person carry the mattress to your bedroom or get your partner or a friend to help you move it, you’re saving yourself a lot of pain, stress and struggling.

I might be sounding overdramatic, but I’ve experienced the struggle of trying to get a bed in a box mattress up the stairs. Before I moved house last year, I had the Emma NextGen Premium mattress delivered in its box, waiting to be set up once I got to my new house. Maneuvering it into a moving van, then into my house and up the stairs to my bedroom was one of the hardest parts of the move, so make sure you get some help with this! 

Simba Hybrid Essential Mattress Topper, rolled up and wrapped in plastic film

(Image credit: Tom May)

2. Using the wrong cutting tools

As your bed in a box mattress will arrive tightly vacuum sealed in plastic, you’ll need to cut into it for the mattress to unfurl. But it’s important that you use the right cutting tools to open it. Some manufacturers will provide cutting tools in the delivery box, but if they don’t, you’ll want to be extremely careful using a knife or pair of scissors.

Firstly, as the mattress is so tightly packed, it’s very easy to accidentally cut into the mattress which can damage the cover and material of your mattress. If you decide the mattress isn’t for you, a cut or tear will mean the brand won’t take it back or refund you properly. Secondly, the mattress will start to inflate as you open it which can bump into you, causing you to accidentally cut into the mattress or hurt yourself. With the cutting tools provided or with other cutting instruments, go slow and steady to avoid any issues.

3. Unrolling the mattress on the floor

Once you get the bed in a box mattress out of the box, make sure to unroll it on your bed frame and not on the floor. Unpacking your mattress on the floor is one of the most common mistakes you can make, as you’ve just given yourself a whole new struggle of rearranging your mattress. It was already heavy when packed away, but as your bed in a box mattress starts coming to its full size, it can be even harder to maneuver and rearrange, so save yourself the stress and unpack it on your bed frame.

4. Not letting the mattress fully expand

Once the plastic is off, your bed in a box mattress will start to inflate or expand to its full size. While some brands claim your bed in a box mattress is ready to sleep on immediately, others will suggest waiting for at least 24 hours. While your mattress might look like it’s fully expanded, it still needs time to settle into itself after being packed away. If you apply extra pressure to your mattress as it’s still expanding, it can take even longer for it to come into its proper shape and form, so you’re not getting the most out of your bed in a box mattress.

Nectar mattress discounts and deals

(Image credit: Nectar)

5. Taking too long to unpack your bed in a box mattress

If you’re about to move to a new house or you don’t have anywhere to store your old mattress, it’s easy to keep your bed in a box mattress in its wrapping for a prolonged period of time. But if you leave it in the box for too long, you could encounter some issues. Again, it will depend on the manufacturer you buy from, but most brands say you can keep it in the box for up to six weeks. Any longer than that, your mattress might not expand properly and this can void your warranty, as the brand is unlikely to take your mattress back if you haven’t followed the set-up instructions correctly.

6. Forgetting to open a window while unboxing

One of the most common complaints people have about bed in a box mattresses is the smell. As they come wrapped in plastic, some of them tend to have a strong chemical smell. The smell will typically dissipate quite quickly and it’s not harmful but it can be a little unpleasant to be around and sleep near. When you unbox your mattress, make sure to keep a window and doors open to help the smell disappear more quickly.

Bethan Girdler-Maslen
Home Editor

Beth is Home Editor for T3, looking after style, living and wellness. From the comfiest mattresses to what strange things you can cook in an air fryer, Beth covers sleep, yoga, smart home, coffee machines, grooming tools, fragrances, gardening and much more. If it's something that goes in your house, chances are Beth knows about it and has the latest reviews and recommendations! She's also in the know about the latest deals and discount codes from top brands and retailers.


Having always been passionate about writing, she’s written for websites, newspapers and magazines on a variety of topics, from jewellery and culture, to food and telecoms. You can find her work across numerous sites, including Wedding Ideas Magazine, Health & Wellbeing, The Bristol Post, Fashion & Style Directory, TechRadar, CreativeBloq and more. In her spare time, Beth enjoys running, reading, baking and attempting craft projects that will probably end in disaster!