How to make a mattress firmer: 8 fixes to try first
Hi, we’re John and Mimi. “My mattress feels too soft, can I make it firmer?” comes up a lot, and the good news is that the mattress often isn’t the problem. What’s under it, how old it is and even the temperature of the room all change how firm a bed feels. Here are the fixes we’d try, starting with the free ones, plus how to tell when it really is time for a firmer mattress.
The short answer
- Check what’s underneath first. Wide slats, a frame with no center support or a worn box spring let any mattress sink. Our listings call for a solid surface, an adjustable base, or slats no more than 2" apart.
- Add a solid layer. A bunkie board or a smooth sheet of plywood over the slats makes the whole bed feel firmer.
- Rotate it, and flip it only if it’s two-sided.
- Keep the room a little cooler. Memory foam tends to feel firmer in a cool room.
- If there’s a real dip or the mattress is simply too soft for you, no add-on fixes that for long. A firmer mattress does.
8 ways to make a mattress firmer
- Look under the bed. Strip the sheets and check the box spring, slats and center rail. Slats spaced wider than 2", a missing center leg on a queen or king, or an old box spring that dips will let the mattress sag where you sleep, and that feels like “too soft.” Our sagging mattress guide walks through it.
- Put a solid surface under it. A solid platform feels firmer than slats or an adjustable base. If your frame has wide slats, lay a bunkie board or a smooth sheet of plywood cut to fit inside the frame over them. We don’t sell bunkie boards, and plywood does the same job. More in what to put under a memory foam mattress.
- Try the floor for a night, as a test. If the bed suddenly feels right on the floor, the base is the problem, not the mattress. Don’t leave it there long: a mattress needs air underneath, and our warranty page excludes mold.
- Rotate it head to foot. Our care instructions say to rotate the mattress for uniform wear. If you always sleep in the same spot, rotating moves you onto foam that has seen less use. See how often to rotate or flip a mattress.
- Flip it, but only if it’s two-sided. Our 12" iSwitch and 12" BioPosture iSwitch have a medium firm side and a medium soft side, so flipping to the medium firm side is a real change. Most foam mattresses are one-sided; flipping those puts you on the base foam, which isn’t made to sleep on.
- Cool the room down a little. Memory foam tends to feel softer when it’s warm and firmer when it’s cool. A warm bedroom or a heavy comforter can make an all-foam bed feel softer than it is.
- On an adjustable base, try it flat. Raising the head or using zero gravity lets your hips settle and changes how firm the bed feels. If you want maximum push-back, sleep flat. See zero gravity adjustable bed.
- Consider a firm topper, with low expectations. A dense topper can add a little firmness to a mattress that’s still flat and supportive. It can’t lift a dip or bring back worn-out foam, because it just follows the shape underneath. We don’t sell toppers. Our topper vs new mattress guide covers when one makes sense.
Too soft, or sagging? How to tell
| What you notice | Likely cause | What to do |
|---|---|---|
| The whole bed feels soft, and it’s flat | The feel is softer than you like, or the base is giving | Fixes 1, 2, 6 and 7, then a firmer model if it’s still too soft |
| A dip where you sleep | Base sagging, or worn comfort foam | Check the base; see how to fix a sagging mattress |
| Feels fine on the floor | The base, not the mattress | Add a solid surface or replace the box spring |
| Hips sink and your lower back aches | Too soft for how you sleep or what you weigh | Look at firmer models below |
| Mattress is many years old | Normal wear | See how long a mattress lasts |
Mattress fairly new and you see a real dent on a solid surface? Text John a couple of photos with your order number. Defects are covered by the manufacturer’s 10-year limited warranty, and we handle the claim for you. What counts as normal is in our mattress warranty guide.
Who usually needs a firmer mattress?
- Stomach sleepers, because a soft bed lets the hips sink and arches the lower back. See best mattress for stomach sleepers.
- Back sleepers who wake up stiff on a plush bed. See best mattress for back sleepers.
- Heavier sleepers, who sink further into any comfort layer, so a mattress feels softer to them than its label says. See best mattress for heavier sleepers.
Side sleepers and lighter people are the opposite: they usually like a step softer. Our mattress firmness guide explains the scale.
Our firmer mattresses, at today’s prices
If the base checks out and the bed is still too soft, these are the firmest models we sell, plus a medium firm hybrid for people who want coils that push back:
| Pick | Best for | Model code | Queen | King |
|---|---|---|---|---|
| 8" Daisy Firm | Firm, budget price, zip-off washable cover | 8BNV-Q |
$349 | $399 |
| 8" Gel Comfort Reactive | Firm, made for back and stomach sleepers | 8ESSCA-Q |
$319 | $399 |
| 12" Lavender Firm | Firm but conforming, thicker profile | 12BNF-Q |
$579 | $629 |
| 10" EcoCore Hybrid Premium | Medium firm, edge-to-edge pocketed coils | 10HSOY-Q |
$619 | $719 |
| 12" iSwitch Flippable | Medium firm side and medium soft side | 12ISWITCH-Q |
$639 | $769 |
Prices are today’s prices, read live from our catalog, with free FedEx shipping included. A dash means that model isn’t made in that size.
More firm picks by sleep position are in our best firm mattress for back and stomach sleepers guide, and every model side by side is on the mattress comparison chart.
What if it’s too firm instead?
A brand-new mattress often feels firmer for the first few weeks while the foam softens and your body adjusts. Sleep on it every night, keep the room comfortably warm, and give it time; our break-in guide covers what’s normal. A slatted frame or an adjustable base also feels softer than a solid platform. If it’s still too firm after a month, a soft topper or a plusher model like those in our best soft mattress guide is the next step.
12" Lavender - Firm - 12BNF
Our pick when a bed that’s too soft needs replacing: firm support with enough give on top to stay comfortable.
- Firm feel
- 1.5" air foam over an 8.5" Air Grid base
- Queen, king and cal king at today’s prices
From $579 (Queen) · Queen $579 · See sizes & details
12" iSwitch Flippable Two Sided Mattress - Medium Firm/Medium Soft - 12ISWITCH
Not sure how firm to go? Sleep on the medium firm side, and if it’s too much, flip to the medium soft side.
- Two sides: medium firm and medium soft
- Gel memory foam on both sides
- Zip-off machine-washable cover
From $529 (Twin XL) · Queen $639 · See sizes & details
Shop this guide
Ready for a firmer bed? These are where most people start.
- 12" Lavender - Firm - 12BNF, from $579. Firm 12" memory foam.
- 8" Daisy - Firm Mattress - 8BNV, from $249. Firm 8" at a budget price.
- 10" EcoCore Hybrid Premium Soy Foam & Pocket Coil Mattress - Medium Firm, from $489. Medium firm hybrid with pocketed coils.
- Express Mattress Foundation with 6" Grey Wood-Style Legs, from $259. A solid foundation with legs, if your old base is the problem.
Questions we hear a lot
How can I make my mattress firmer?
Start with what is underneath. Slats more than 2 inches apart, a frame with no center support or a worn box spring let any mattress sink. A bunkie board or a smooth sheet of plywood over the slats makes the bed feel firmer. Then rotate the mattress head to foot, flip it only if it is two-sided, and keep the room a little cooler, since memory foam feels firmer when it is cool.
Will plywood under a mattress make it firmer?
Usually, yes. A solid surface feels firmer than slats or an adjustable base, and it stops the mattress from dipping between wide slats. Use a smooth sheet cut to fit inside the frame, and do not put a mattress straight on the floor for long, because it needs air underneath.
Can a topper make a mattress firmer?
A dense topper can add a little firmness to a mattress that is still flat and supportive. It cannot lift a dip or bring back worn-out foam, because it follows the shape underneath. We do not sell toppers.
Why does my mattress feel softer than when I bought it?
New foam softens slightly over the first weeks, and a warm room makes memory foam feel softer. If you see a real dip, check the base first. On a solid, flat surface, a dent that stays can be a defect; text John photos with your order number and we handle the warranty claim.
Which of your mattresses are the firmest?
Our firmest models are the 8-inch Daisy Firm, the 8-inch Gel Comfort Reactive and the 12-inch Lavender Firm. The 10-inch EcoCore Hybrid Premium is medium firm with pocketed coils, and the 12-inch iSwitch has a medium firm side. Prices on the guide update live.
Not sure what’s making it soft?
Text John what you’re sleeping on, how old the mattress is, what’s under it and where you feel it sink. He’ll tell you honestly whether a fix for the base will do it or whether a firmer mattress makes more sense. Text or call 818-924-3744, 6 AM to 9 PM Pacific, or take the 60-second mattress quiz.
Written by John & Mimi Venti, MimiJohn. Setup, care and warranty details are from our product listings; the other tips are general guidance, not medical advice. Prices are read live from our catalog and update automatically.