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By Jo Plumridge published 28 June 22

A mattress that’s too soft for your body type and sleep style can cause neck and back pain over time, so it helps to know how to make a mattress firmer if yours has lost the support you need. 

It’s normal for even the best mattresses to show signs of softening after years of heavy use, but luckily there are ways to reverse this - with some caveats that we'll cover below.

While mattress firmness is subjective, a medium-firm feel suits most people, whether you opt for a hybrid, innerspring or memory foam mattress. Softer mattresses, while snug at first, can cause lower back pain in some people by throwing the spine out of alignment. 

Whatever the cause of your bed's softness, here’s how to make a mattress firmer And if you decide to upgrade instead, check out our 4th of July mattress sales guide for the latest offers.

Our tips should hopefully help you firm up your mattress quickly. But if yours is showing signs of serious sagging, there's only so much you can do (we have extra advice in our feature on how to fix a sagging mattress). 

In a rush? Then here are our top tips for how to make a mattress firmer:

Buying a mattress online has big benefits (not to mention cheaper prices thanks to an abundance of mattress sales), but one of the downsides is figuring out what firmness would suit you. 

That's why manufacturers offer at-home trial periods. These range from 100 nights (the average length) up to a whole year. If you're still within your trial period, act now and return your too-soft mattress for a firmer model. Most brands offer free returns and exchanges, though some, like Saatva, will charge a processing fee.

If your mattress is outside of the trial period, check the warranty to see if you're covered for a certain amount of sagging / sinkage. Just keep in mind that sagging isn't the only cause of softer mattresses - some are just made that way.

Most mattresses should be rotated every three months to spread out wear and tear and to prevent deep sagging in one particular spot. However there are a few mattresses that can’t be rotated – usually models that have areas of specific lumbar support (also called zoned support). Precious few, such as traditional innerspring mattresses, can be flipped. 

If your memory foam or hybrid mattress can be rotated, do this first as the softness you're currently feeling around your back and hips will then be at the bottom of the bed. Our article answering how often should you flip or rotate your mattress has extra tips.

In general bed toppers are used to soften a mattress, but the huge variety now available means you’ll also find toppers designed to make a mattress firmer. These can also help isolate motion from a restless bed buddy. 

Latex mattress toppers are your top option for adding firmness, with the material (made from the sap of rubber trees) providing a firmer, more responsive surface. Luxury sleep specialist Saatva makes a great latex topper, priced from $245 at Saatva (opens in new tab) (see our Saatva mattress sale guide for the latest deals).

If you prefer memory foam, look for a hard foam topper. Our best mattress toppers guide runs you through this year's top-rated picks for all sleep scenarios.

Another sure-fire way to make a mattress firmer is to place it on a more supportive bed frame, platform or base. This will add firmness from underneath, making your mattress feel firmer overall. A new bed frame is also likely to cost a lot less than a new mattress. 

Firm edge divans are an excellent choice for a firmer bed as they’re designed with solid springs and a rigid wooden-sided frame. A slatted base designed to be rigid with no give is another great choice for adding firmness. 

Just don't pick one where the slats are spaced too far apart otherwise your mattress may (especially a foam one) will dip through the slats, making it feel softer overall.

While putting your mattress on the floor will make it feel instantly firmer, there are some drawbacks to this approach. Firstly, make sure that your mattress can be placed directly on the floor for sleeping. Some mattress warranties, for example, will be voided by this approach (so you won't be covered for damage). 

You mattress will also pick up a lot more dust and dirt on the floor, and bugs (including bacteria) will find it easier to join you in bed. Put a thin rug underneath the mattress for protection and clean it regularly (see our guide on how to clean a mattress for tips) to keep germs, stains and other nasties at bay.

Most of us know that an overly hot bedroom makes it difficult to fall asleep and to stay asleep, but did you know it can also affect how soft or firm memory foam feels. If your bedroom is too warm, foams will soften and lose their supportiveness. 

Hybrid mattresses with springs are usually fine, but cheaper versions could also lose firmness and stability in the foam areas. To make your mattress firmer at night – and to sleep better generally – switch off the heating or program your smart thermostat to reduce the heating an hour or so before bed.

When it comes to how to make a mattress firmer, you'll see this hack pop up a lot. And placing a thin slab of wood beneath your mattress will do the trick, but, as with placing your mattress on the floor, there are some caveats with this approach.

Namely, it’s not suitable to use with many materials. Memory foam needs to breathe properly or you could run the risk of mold and bacteria growing on the material. Not only is this bad news for your health, it would void your mattress warranty. 

If you do want to try the plywood mattress hack, we’d strongly suggest speaking to your mattress’ manufacturer first to check if it’s allowed and to see if they can offer a better solution. Sometimes they'll surprise you with a free topper to boost firmness.

Different types of moisture soften a mattress – this is particularly common in humid areas, houses with poor insulation, or if you live close to the beach. If you suffer from night sweats, all that sweat and release of body oils can also lead to a mattress losing its firmness over time. 

A quick fix is to take your mattress outside when it’s sunny and warm and leave it to air for a few hours, with the heat and sun naturally drawing out moisture. Not only will this make your mattress feel firmer, it will also kill off any bacteria, germs and mold caused by the dampness.

A common misconception is that ultra-firm mattresses are the better option for good back health and to reduce pain. In fact, a medium-firm mattress tends to suit the vast majority of sleepers more. This is because medium-firm beds keep the spine in neutral alignment, yet they aren’t so firm that they become painful to sleep on.  

Your body weight and sleep style will also play a big part in how soft or firm a mattress should be. Lighter weight sleepers can get away with a softer mattress than those of a heavier weight, as they won’t sink so far into the mattress. If you’re a dedicated side sleeper, you’ll actually want a slightly softer mattress that cradles your shoulders and hips.

Back and combo sleepers will thrive with medium-firm mattresses, but if you’re a stomach or back sleeper, look for a mattress at the firmer end of the scale to keep your head from sinking into the mattress and throwing your spine out of alignment. 

If you've decided to opt for a new bed, we've rounded up some of our favorite medium-firm mattresses below. To boost your sleep comfort further, see our guide to this year's best pillows for all budgets.

Jo is an experienced mattress writer and reviewer who writes about various sleep products, including pillows, mattress toppers and weighted blankets. What Jo doesn't know about mattress tech isn't worth knowing.

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