What if Your Mattress Is Too Big for Your Bed Frame?

You have a lovely bed frame that you want to put in your bedroom, but it’s a size smaller than your current mattress. Mattresses are expensive, and you would like to keep yours if you can. So what do you do when your mattress is too big for your bed frame?

An overly large mattress will not sit properly in an undersized bed frame. This can result in uncomfortable bumps and other issues that could disturb your sleep. Depending on your mattress type and access to tools, you can resize your mattress to fit a smaller frame.

If your mattress is too big for your bed frame, you have a problem. Luckily, it’s a problem you may be able to fix without a trip to the mattress store. Read on and learn more about fitting mattresses to frames and vice versa!

Should the Bed Frame Be Bigger Than the Mattress?

Your bed frame should be large enough to fit your mattress comfortably. A little extra frame room around your mattress is better than a mattress that is too large for its frame. However, too much space leads to gaps that are inconvenient and can even be dangerous.

These are the standard mattress sizes:

Type of BedDimensions
California King72″ X 84″ (183 X 213.5cm)
King76″ X 80″ (193 X 203.5cm)
Olympic Queen66″ X 80″ (167 X 203.5cm)
Queen60″ X 80″ (152 X 203.5cm)
Full XL54″ X 80″ (137 X 203.5cm)
Full54″ X 75″ (134.5 X 190.5cm)
Twin XL38″ X 80″ (96.5 X 203.5cm)
Twin38″ X 75″ (96.5 X 188.0cm)

While mattress makers generally keep their products very close to these guidelines, you will find measurements vary more amongst bed frame manufacturers. And when you get into antique or custom bed frames, things can get complicated.

If your bed frame is too small, you will encounter lumps and dips when you try to force it into the frame. Additionally, if you are using a platform bed frame, an overly large mattress will be prone to sliding. Bumpy mattresses are not great if you’re looking for a restful slumber, and slipping onto the floor when you roll over makes things even worse.

Furthermore, if your mattress is too big for your bed frame, you’ll also find there is an uneven weight distribution on the frame. The extra tension against the footboard and headboard can damage the frame, and the friction against the sides can lead to torn mattress covers.

If your bed frame is too large for your mattress, you can run into other problems, which I will discuss later. However, an overly small frame will cause many more issues than a frame that is too big.

Due to this, most bed frame makers tend to err on the side of making their frames a bit larger than the standard size, while mattress manufacturers generally make their mattresses a wee bit smaller.

How Much Bigger Should a Bed Frame Be Than the Mattress?

A bed frame should be no more than five inches bigger than a mattress in any direction. This depends on the frame type – for example, the gaps created by sleigh or 4-poster bed frames are more dangerous than gaps on platform beds.

If you have ever dropped your keys or a cell phone into the space between your mattress and bed frame, you know how annoying this gap can be. However, a big gap is more than just a nuisance. Children or disabled adults who get caught between a mattress and bed frame can die of choking or suffocation.

Since platform beds are generally flat platforms, there is no suffocation risk should you put a smaller mattress on a bigger platform. However, anything bigger than five inches may make getting out of bed awkward. Additionally, if you have sideboards, you will likely want there to be even less space between your mattress and frame.

But can you reduce the size of your mattress? With a little work, you can cut your overly large mattress so that it better suits your frame. A mattress with spring coils will be more challenging than resizing a foam mattress, but almost any mattress can be resized with the right tools.

How to Reduce the Size of Your Mattress

If your mattress is too big for your bed, don’t worry – cutting it down to size is easy, especially if it’s a foam mattress. Here are the steps you’ll need to follow.

1. Take Measurements

Using a tape measure, get the exact dimensions of your bed frame and the space available for your mattress. Now get the precise measurements of your mattress.

Like carpenters like to say, “measure twice, cut once.” You’ll need the best possible fit between your frame and your resized mattress.

2. Remove Your Mattress Cover

If your mattress cover does not have a zipper, you will have to slice it at a seam to open and then remove it. This will expose the foam heart of the mattress.

However, many mattress covers have zippers so they can be removed for washing. If your mattress has a zipper, you can reuse it.

All you need to do is pull the mattress cover taut, put the excess on the bottom of the mattress, and then cover your resized mattress with bedding.

If you have to slice your mattress cover, you will need a replacement.

I recommend the SafeRest Premium Mattress Protector (available on Amazon). This cover is available in several sizes and will protect your newly trimmed mattress from:

  • Urine
  • Sweat
  • Allergens
  • Dust mites

3. Mark the Foam

Mark the foam at the places where you need to cut. Measure carefully and make sure your lines are straight, as a crooked cut may throw your fitting off. A second person to hold the tape measure in place will be very helpful. However, this isn’t necessary as long as you are careful.

4. Cut the Foam

The best tool for DIY foam-cutting projects is an electric carving knife, like the Proctor Silex Easy Slice Electric Knife. The Easy Slice will, as per its name, make slicing through foam easy.

For best results, place a 2×4 board along the line to cut your foam. Kneel on the 2×4 as you are cutting. This will compress the foam and make your job easier.

If your mattress has inner springs, things will be a bit more difficult. You will need to cut along your marked line with a utility knife until the springs are exposed, then cut them with a Dremel tool or bolt cutters.

After snipping the springs, bend each bit of metal until it forms a flat edge, then tie the springs using twine or cloth.

Be careful when you work on this step. If it’s done poorly, you could wind up rolling over on a sharp spring one night or discover a spring poking from the side of your new mattress cover. If you have a spring mattress, you may be better off “springing” for a new one.

Key Points

You want your mattress to fit your bed frame. However, if your mattress is too big for your bed frame, don’t worry – you have options. You won’t need to spend money on a new mattress and spend time breaking it in – there’s a chance you can easily use your old one just fine! Happy slumbers!

Leave a Comment