"When someone tells me their mattress feels too soft, my first question is whether it is the bed or the base. Half the time the mattress is fine and the box spring underneath has given out. If the mattress itself is just plusher than they like, a firm topper is the cheapest honest fix, our So Sleepy firm topper is a queen for about $339, and it changes the feel without throwing out a good bed. What I will not do is sell someone a topper to cover up a mattress that is actually finished."
Talia Grose, sleep specialist, Mattress Miracle
A too-soft mattress is one of the most common complaints we hear, and the good news is that several fixes genuinely work. A mattress can feel soft for three different reasons, and the right fix depends on which one you have: it was always softer than you prefer, the comfort foam has softened with age and body heat, or the base under it has worn out. A medium-firm surface is the evidence-backed sweet spot for most adults, a 2015 systematic review in Sleep Health, the journal of the National Sleep Foundation (Radwan et al., 2015), found that very soft and very firm both scored worse than medium-firm for sleep quality and spinal alignment. This guide covers the seven firming methods that actually work, which ones are myths, and the honest point where the answer is a new mattress rather than another patch.
In This Guide
- Why Is My Mattress Too Soft?
- 7 Ways to Make a Mattress Firmer
- Which Methods Actually Work (and Which Are Myths)
- Firmness, Sleep Position, and Your Back
- When to Stop Patching and Replace
- Frequently Asked Questions
Reading time: 8 minutes
Why Is My Mattress Too Soft?
Before you try to firm it up, work out why it feels soft, because two of the three causes are not really about the mattress at all.
- It was always too soft for you. A plush or pillow-top feel that is wrong for your body or sleep position. Firming methods work well here.
- The comfort layers have softened. Foam loses some firmness over the first months (normal break-in) and more over years of body heat and weight. A topper restores surface firmness.
- The base under it has failed. A worn box spring, broken slats, or slats spaced too far apart make a perfectly good mattress feel soft and saggy. Fix the base, not the bed.
There is one more possibility that no firming trick can solve: a true sag, a permanent dip you sink into and roll toward. That is a failed core, not a softness preference, and it is covered in our sagging-mattress guide. The rest of this article is for a structurally sound mattress that you simply want firmer.
7 Ways to Make a Mattress Firmer
Here are the seven methods, roughly in order of how well they work for a sound-but-soft mattress.
| Method | How well it works | What to know |
|---|---|---|
| 1. Add a firm mattress topper | Best surface fix | A firm Dunlop latex or high-density foam topper raises the surface firmness. Our firm So Sleepy topper is about $339 in a queen. |
| 2. Replace or fix the foundation | Often the real fix | A worn box spring or broken slats make a good mattress feel soft. Slats should sit 3 inches apart or less with centre support. |
| 3. Slide plywood or a bunkie board underneath | Quick, temporary | Adds rigid support under a failing base. A fix for tonight, not a permanent solution. |
| 4. Lower the bedroom temperature | Memory foam only | Memory foam softens with heat. A cooler room (and a breathable cover) keeps it firmer. |
| 5. Rotate it 180 degrees | Mild but worth doing | Evens out wear so you are not always lying on the softened spot. Do it every few months. |
| 6. Flip it (only if double-sided) | Only some beds | Works on a true flippable mattress. Most modern beds are one-sided, and flipping those makes them worse. |
| 7. Let a new mattress finish settling | If it is brand new | A new bed can feel soft until it fully expands and breaks in over a few weeks. Make sure it is unrolled flat first. |
Which Methods Actually Work (and Which Are Myths)
If you only do one thing, add a firm topper or fix the base. Those two solve the large majority of too-soft complaints we see on the floor.
The firm topper, done right. Topper material matters more than thickness. Firm Dunlop latex gives the most supportive, durable lift; high-density polyurethane foam (look for 1.8 lb/ft³ or higher) is the next best. Avoid soft memory-foam or featherbed toppers here, they will make the bed softer, not firmer. A topper firms the surface, but remember it cannot rescue a collapsed core underneath.
The temperature lever for memory foam. Memory foam is temperature-sensitive: it gets softer as it warms to your body. Keeping the bedroom cooler, around 18 to 20 degrees Celsius, and using breathable bedding noticeably firms up an all-foam bed. This does nothing for an innerspring or latex mattress.
The myths. A few popular tricks do little or backfire:
- Flipping a one-sided mattress. Only true double-sided beds are built to flip. Flipping a one-sided mattress puts the unsupported base layers on top and ruins the feel. See our flip-or-rotate guide.
- Putting the mattress on the floor long-term. It can feel firmer briefly, but it traps moisture, risks mould, and voids most warranties.
- Tightening the sheets or airing it out. Harmless, but they do not meaningfully change firmness.
For the foundation side of the fix, our box spring vs foundation vs platform bed guide covers what to put a mattress on, and the mattress topper guide goes deeper on materials.
Firmness, Sleep Position, and Your Back
Firmer is not automatically better. The goal is a surface that keeps your spine in a straight, neutral line, and the right firmness depends on how you sleep. Medium-firm is the default for most adults, but adjust from there:
- Side sleepers usually want medium to medium-soft, so the shoulder and hip can settle in. Over-firming a bed for a side sleeper can create pressure points and actually hurt alignment.
- Back sleepers do well at medium-firm, which fills the lower-back curve without a gap.
- Stomach sleepers and heavier sleepers usually need it firmer to stop the hips sinking.
If you are firming a bed mainly to help your back, aim for medium-firm rather than the hardest possible surface. A board-hard bed relieves no pressure and can leave a gap behind your lower back.
When to Stop Patching and Replace
Firming tricks buy time on a good mattress. They are wasted money on one that is finished. It is time to replace, not patch, when:
- There is a dip you roll into, or a sag that returns within days of rotating. That is core failure. Measured with a taut string corner to corner, a sag past about 1.5 inches on an innerspring or hybrid (or about 0.75 inches on dense foam or latex) is a replace.
- You can feel or hear broken coils, or the foam has visibly crumbled.
- It is simply old. Most mattresses are due at 7 to 10 years. Our mattress lifespan guide breaks it down by type.
"I would rather lose a topper sale than send someone home to patch a dead mattress. If the core is gone, a topper just hides it for a month. When it really is time, you do not have to overspend: a firm queen like our Spinal Rest is around $575, and a pocket-coil hybrid like the ComfortCare Dalton in its firm build is about $1,619. We will tell you honestly which side of that line your mattress is on."
Brad Grose, founder, Mattress Miracle, family owned in Brantford since 1997, with 40+ years in the mattress industry
If you have decided it is time, browse our firm mattresses or the medium-firm range that hits the Radwan sweet spot, or call us and we will fit you in person.
Frequently Asked Questions
How can I make my mattress firmer without buying a new one?
The most effective method is adding a firm high-density or latex mattress topper. You can also replace a worn foundation or box spring, place plywood or a bunkie board under the mattress, lower the bedroom temperature if it is memory foam, and rotate it regularly. These work on a structurally sound mattress, not one with a permanent sag.
Does putting plywood under a mattress make it firmer?
Yes, temporarily. A sheet of plywood or a bunkie board adds a rigid surface that stops a mattress flexing into a worn base, which firms the feel. It is a short-term fix, though. If the base has failed, replacing the foundation is the proper solution; if the mattress core has failed, plywood will not save it.
Can you make a memory foam mattress firmer?
Somewhat. Memory foam softens with heat, so keeping the bedroom cooler (around 18 to 20 degrees Celsius) and using breathable bedding makes it feel firmer. A firm topper on top also helps. But foam that has permanently softened or developed a body impression cannot be restored to its original firmness.
Will a firmer mattress help my back?
Up to a point. Research links medium-firm surfaces to the best sleep quality and spinal alignment for most adults, while very soft and very firm both perform worse. So if your bed is too soft, firming it toward medium-firm can help, but a board-hard surface is not better and can create pressure points, especially for side sleepers.
Is my mattress too soft, or is it sagging?
Too soft means the whole surface gives more than you like but springs back when you get up. Sagging means a permanent dip that stays when the bed is empty and that you roll toward. Firming methods fix the first; the second is core failure that needs repair or replacement. Our sagging-mattress guide covers that case.
Sources
- Radwan A, Fess P, James D, et al. Effect of different mattress designs on promoting sleep quality, pain reduction, and spinal alignment in adults with or without back pain; systematic review of controlled trials. Sleep Health. 2015;1(4):257-267. PubMed
- Sleep Foundation. How to Make Your Mattress Firmer. sleepfoundation.org
Visit Our Brantford Showroom
Mattress Miracle
441 1/2 West Street, Brantford, Ontario
Phone: (519) 770-0001
Hours: Mon-Wed 10-6, Thu-Fri 10-7, Sat 10-5, Sun 12-4
Not sure if your mattress can be saved or needs replacing? Bring us the details, or come lie down on a few firmness levels. Our team does not work on commission, so you will get an honest read, white glove delivery, and old-mattress removal if it is time for a new one.