How To Resize A Mattress

Investing in the right mattress plays a pivotal role in helping you get restorative sleep, which is one of the best ways of maintaining and improving your health. But what happens when you want to change your bed or shift to a new home? Should you change your existing mattress, too, or is there a practical way to customize it to suit your new space?

While investing in a new mattress can help unlock your ability to sleep better, you don't need to get rid of your old mattress every time you get a new bed. By learning how to resize your mattress, you can always upsize or downsize it whenever you want to purchase a new bed. 

To help sleepers get a handle on how to resize a used mattress, we break down the vital details piece by piece. With this guide, you can rest assured of having the knowledge to resize your existing mattress to suit your unique needs and deliver a good night's sleep night after night.

What You Need

First things first, get your tools ready. Normally, you should have an easy time finding these tools at your local hardware stores, as they're pretty common. They include:

  • A sewing machine (or needle)
  • A pair of scissors or a sharp knife
  • Tape measure
  • Wax
  • Thread
  • Pliers for better grip

Ensure you get all these tools to avoid making multiple trips back to the store.

How to Cut a Mattress: A Step-by-Step Guide

It will help if you always cut your mattress with caution, as whichever tool you use will have sharp edges. Below are some of the steps that can help you resize your mattress.

Step 1: Determine the Dimensions and Size of the Mattress that You Want

It's always wise to consider the mattress thickness you want to have. For instance, if you're fitting a memory foam mattress into a small space, such as a van or boat, it shouldn't be too tall. 

And since memory foam can be easily flattened, it might be good to have a medium-density layer on top of a high-density one. This will ensure comfort and also help prevent your mattress from flattening. Some memory foam mattress brands are usually constructed with this in mind and feature several layers with different types of foam. 

Before you start cutting, you should also consider the dimensions you need. How much foot and head space do you want? Do you want to turn your king-size mattress into a queen mattress? These considerations are especially crucial when custom-cutting memory foam mattresses for a smaller bed, a van, or a boat. 

Here's a list of different mattress types and their measurements. 

Mattress type


California King 

72" × 84" 


76" × 80" 


60" × 80"


53" × 75"

Twin XL 

38" × 80"


38" × 75"

Step 2: Take off the Cover 

If your memory foam bed has a cover, remove it and put it somewhere clean. You may need to cut open some mattress covers. If this is the case, make an initial cut with scissors to get into the cloth. Once this is done, make a vertical cut along the edge of your mattress by pressing the scissors against the fabric. Only cut as much as needed to take out the foam mattress. Remember to check for zippers before you cut any material, as most manufacturers add zippers. If your mattress had stains or it was reeking of vomit smell, you may want to take this opportunity to clean the cover and get rid of the unpleasant smell.

Step 3: Measure and Mark the Section You Want to Cut

Using a ruler, measure and draw the line of the cuts you want to make. Make notches every 18" to 24". Drywall squares can help you cut long pieces of foam straight. You can also measure your desired dimensions onto cardboard and use this as a template for your cutting job. 

Step 4: Cut the Mattress Carefully on a Flat Surface

Make sure you place your foam mattress on a flat, stable surface. And before cutting, it's also wise to make yourself aware of your blade's angle. Generally, your knife should be parallel to your mattress' height, unless you want to create an unusual shape or cut your mattress in half horizontally. 

As you cut your mattress, don't put pressure on it as its shape will change. If your knife or pair of scissors is too short to cut through the layers, start with a shallow cut and then a deeper cut. Remember, the bottom section of your mattress may have a different density, and this can significantly affect your cutting action. For instance, harder foam is harder to cut, while the soft foam is more likely to warp out of place. So, if you're cutting soft foam, consider placing something like cardboard or drywall squares on either of its sides to avoid warping your mattress.

Check the line to confirm whether you've cut through the entire length. Bear in mind that your mattress may be thick, so feel free to make two cuts if necessary. Don't flip over your bed unless you're certain the line on both sides of the mattress will be the same.

Step 5: Trim Off the Excess Foam Layer and (Re) Fit Your Mattress Cover

Trim off the excess foam but don't stress too much about presentation. After all, you'll be putting the mattress cover back on. Because your mattress is now smaller, it's time to decide whether you'll be folding over the excess cloth, buying a new mattress cover, or re-stitching the old one. 

Also, think about what you'll do with the excess foam material before cutting it into smaller pieces, as you could use it to make a mat, a pillow, or even another mattress. The smaller the leftover pieces are, the minimum your options will be. Once you’re done with the refitting process, you may want to consider washing your mattress. Remember, cleaning a mattress not only extends its useful lifespan but also helps improve your sleep quality.

Is it Possible to Cut Your Latex Mattress to Adjust Sizing?

One thing that makes all-latex mattresses a dynamic investment is the ability to make them bigger or smaller as the need arises. Instead of buying a new mattress, you can adjust your latex mattress to meet your unique specifications.  
Even with the same mattress brand, the different times of production may mean facing variability in the quality of your mattress. Plus, you may encounter the challenge of not knowing the ILD ratings or the original manufacturer of your mattress, thus risking getting stuck with a much poorer-quality .

Have you ever owned a latex mattress? If so, you understand how comfortable and pressure-relieving it is, and perhaps you don't want to purchase a new latex mattress should you need to downsize. And even if you know your bed's original ILD ratings, getting an exact match for your existing mattress is virtually impossible. 

While you can customize a bad mattress by stacking latex foam layers on top of each other, resizing is much easier than dealing with a professional product.

Consider using an electric carving knife to make your mattress smaller. When held perpendicularly, these knives can help cut a straight edge through the several foam layers that comprise your mattress. If you have a Talalay latex foam mattress, cutting right through the holes will create the straightest edge possible.

How to Make Your Mattress Bigger

Resizing your mattress to fit a smaller space is relatively straightforward, as described above. But what happens if you want a bigger mattress? For instance, is it possible to turn your existing Queen mattress into a King size mattress with considerable ingenuity on your part? 

Here's how you can make your old mattress bigger. 

The Cut-and-Buy Method

One effective way of creating a King size mattress is by first cutting down your Queen size mattress to make a Twin XL. Once you've cut your existing mattress, buy another Twin XL bed and place them side-by-side. 

By doing this, you'll be creating a split Eastern King mattress that's best suited for couples. However, this is probably the most expensive solution since a 9-inch Twin bed from the Talalay mattress brand costs about $1200. 

Lucky for you, there's yet another viable fix - extending your mattress on each side. Here, you'll need to add a 16" by 80" foam to each side of the Queen mattress, which essentially creates an Eastern King. The only real drawback with this fix is that you'll need to use an exact match to your old bed to make the same firmness. Plus, if your bed features several layers with different ILD ratings, you might have to spend more to buy the additional foam.

The Rotation Method

Another alternative solution is to rotate your bed 180°. That way, you'll only need to adjust your mattress' foot portion. A Queen size mattress basically measures 80" by 60", so you can trim a small piece of foam off its edge to extend your mattress with a 20" by 78" piece. 

This will essentially turn your mattress into an Eastern King size model, and while the firmness level won't match all your bed's layers, your feet will enjoy that extra cushioned surface. With this procedure, you'll only be extending the foot of your bed, so you won't need an exact match for quality, thickness, and firmness with your existing mattress. 

Here, you can use any latex foam, including the potential for opting for scraps. A small piece of foam will only cost about half the price of a new mattress. 

Generally, there are two ways of ensuring your newly added scrap piece of foam remains intact with your mattress:

  • Using a spray adhesive to glue different foam layers together for stability and firmness
  • Purchasing a new mattress cover and ensuring that all pieces of foam firmly fit inside your cover without any movement

Importance of Resizing a Mattress

Now you know how to resize your mattress, but why is it crucial for sleepers to resize their mattresses? Of what importance will it be to them? 

Here are some of the benefits of resizing your mattress. 

To Preserve the Same Feeling of Comfort

After sleeping on your mattress for some time, you may get attached to it and develop a connection. For instance, patients with hypermobility syndrome may need specific mattress types to sleep on. Once the bed you have becomes your only comfort zone, changing it doesn't guarantee the same. 

Aside from that, many sleepers enjoy the luxurious comfort offered by their mattresses, and they want to experience the same feeling of comfort even with a different size. If you fall into this category, you may wish to keep your old mattress when you change your bed. Fortunately, you can continue enjoying the comfort you're used to even on a different bed by resizing your mattress.

Related Content: Signs your bed is causing back pain

You Don't Have to Change Your Mattress every time You Change Your Bed

Sometimes it becomes crucial to get rid of your old bed and buy a new one. Over time, you may want to downgrade or upgrade the bed. 

If you're going for a King size bed, you'll need a King size mattress. And if you have a smaller bed, a smaller mattress will do just fine. So, does this mean every time you purchase a new base, you should also buy a new mattress? 

Not at all. 

As mentioned earlier, if you learn to resize a mattress, you can always change it anytime you wish to buy a new base. Rather than having many mattresses in your home, why not have one that fits all bases and serves all purposes? Besides, changing a luxurious mattress may feel like losing something of great importance in your life.

Related Content: How to fluff a pillow

Investing in a New Mattress Is Expensive

There are specific types of mattresses that are quite pricey. And once you've purchased one with all the specifications you need, you might not want to let go even after changing your bed. 

If you're willing to spend money on a new mattress, you can quickly get another one with the same preference and ILD ratings. However, if you're not ready to invest in expensive mattresses, resizing your mattress is one possibility you may want to consider.

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Closing Thoughts

There you have it! As you can see, resizing your mattress isn't as challenging as you'd thought. With the right tools and skills, you'll have your ideal mattress in no time. However, keep in mind that altering your bed in any way will automatically void the warranty your manufacturer provides.

But if you see no other alternative to customizing your mattress and are okay with voiding your warranty, feel free to proceed with your DIY project. Don't forget to deep clean or renew your mattress outer cover to make it look brand new again.

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