How to Make a Mattress Firmer

Ever woken up feeling like you’ve been swallowed by your mattress? Maybe it was all comfy and plush at first, but now it’s just a saggy mess that leaves your back aching. No need to chuck it out (just yet) — there are plenty of ways to firm up your mattress and bring back that much-needed support.  

For anyone hoping to get their mattress feeling firmer, we’ve rounded up 10 top tips to try. And if all else fails, at least you’re in the right place to find a new mattress that offers that firmness you crave. Scroll on to find out exactly how to make your mattress firmer. 

1. Flip it or rotate it 

Some mattresses are designed to be flipped, others just rotated. Either way, giving your mattress a spin can help distribute wear and prevent those pesky dips that make it feel too soft. Though, do remember to check whether your mattress is supposed to be flipped and rotated, or just rotated, before you get started. Some mattresses are one-sided, meaning you should only sleep on one side of the mattress. 

2. Get a mattress topper 

Most people think mattress toppers are only for making beds softer, but there are firm ones too! Look for memory foam or latex mattress toppers specifically designed to add support rather than cushioning. 

3. Check your bed frame 

A weak or broken bed frame can make your mattress feel less supportive. And, just like mattresses, bed frames ought to be replaced 7-10 years. If you’ve got slats, you’ll want to check that they’re not bending or broken. A solid base (like a peg board) underneath can work wonders for extra firmness.  

4. Let it air out 

Sometimes, moisture build-up can make a mattress feel softer over time. Strip the sheets off and let your mattress air out for a few hours—better yet, take it outside for some sunshine (if you trust the British weather, that is!). 

5. Lower the room temperature 

Memory foam mattresses, in particular, can soften up when they get too warm. Try turning down the heating a bit at night and see if your mattress feels firmer in the morning. 

6. Use peg boards 

For an instant fix, slide a piece of peg board (that’s basically a thin sheet of wood with little holes in it for ventilation) between your mattress and the bed frame or slats. It’s a cheap and effective way to boost support, though it might not be the most breathable solution. And you should also be aware that if you suddenly find your bed making strange noises in the middle of the night, the peg board is the likeliest culprit! 

7. Replace the box spring 

If you’ve got an old box spring bed base, it might be losing its shape and support. Replacing it (or switching to a solid platform) can make a noticeable difference in mattress firmness. 

8. Try a mattress firming pad 

Not quite the same as a topper, a mattress firming pad is a thinner layer that sits on top of your mattress and provides extra support. They’re often made of dense foam and can be a good middle ground between a topper and a full replacement. 

9. Give it time 

If your mattress is brand new, it might just need a little time to break in and settle into its intended firmness level. Some mattresses feel softer initially but firm up with use. 

10. Consider a new mattress 

If you’ve tried all of the above and your mattress is still leaving you feeling like you’re sinking into a marshmallow, it might be time for an upgrade. Look for a firm or extra-firm mattress that provides the support you need. 

How to make a mattress firmer FAQs 

How do I know if my mattress is too soft? 

If you wake up with back pain, feel like you’re sinking too much, or struggle to get comfortable, your mattress might be too soft. A lack of proper support can lead to poor spinal alignment. 

Can I make a memory foam mattress firmer? 

Yes! Try turning down the temperature on the radiator in your bedroom, using a firm mattress topper, or placing a plywood board under the mattress for extra support. 

Will a mattress topper really make my bed firmer? 

Absolutely—just make sure you choose a firm topper made from memory foam, latex, or high-density materials designed for support rather than plush comfort. 

How often should I rotate my mattress? 

Ideally, every three to six months. This helps distribute wear and prevents soft spots from forming. 

Is it bad to put plywood under a mattress? 

Yes and no. While plywood can add firmness, it is also likely to reduce airflow, which could lead to moisture build-up over time. If you’re considering using a sheet of wood to make your mattress firmer, we’d recommend using peg board rather than plywood to enhance ventilation. You’ll also want to consider lifting the mattress occasionally to let it breathe. 

Final thoughts 

A too-soft mattress can be a real pain—literally. But before you go mattress shopping, try these tips to firm things up. A simple tweak could make all the difference and save you a huge chunk of cash in the process!