How to Make a Mattress Firmer: 7 Proven Methods

Not all softness is created equal. New mattresses feel plush during the break-in period, while older beds sag because support foams are compressing. Place a broom handle across the mattress while you lie down; if the gap exceeds 1.5 inches at the hips, structural support is fading and temporary fixes may only buy a few months.

Check the foundation too. Slats more than three inches apart or aging box springs can flex under weight, making even firm mattresses feel mushy. Stabilize the base before you blame the mattress.

Swap squeaky box springs for a solid platform, adjustable base, or slatted frame with closer spacing. Many Amazon platforms include center support legs that stop the middle from bowing. A rigid base can add the equivalent of two firmness points instantly.

Slide a ¾-inch plywood sheet or dedicated bunkie board between the mattress and slats to remove flex. Wrap the board in breathable fabric so it doesn’t trap moisture, and confirm your warranty allows this modification. This trick is especially effective for foam mattresses on flexible metal frames.

Counterintuitively, toppers can make mattresses firmer when you choose dense latex or high-density foam. Look for ILD ratings above 30 or toppers specifically marketed for orthopedic support. Keep thickness to two inches so you reinforce the surface without feeling like you bought a new bed.

Rotating head-to-foot every one to three months redistributes wear patterns that create soft zones. If you own a double-sided mattress, flip it twice per year so both surfaces carry the load evenly. Mark a rotation schedule on your calendar or tie it to routine chores.

Memory foam softens with heat. Lower the thermostat to 65-67°F or run a fan to firm up the surface, especially during summer. Pair the temperature shift with moisture-wicking bedding so you don’t trap warmth under quilts.

Some mattresses feature zippered covers that let you swap foam layers. Replacing a plush 2-inch topper with a dense latex layer can revive support without buying a full mattress. Contact the manufacturer for compatible inserts and keep receipts in case you need future warranty help.

A lofty pillow can exaggerate softness by forcing your spine into a curve. Align pillow height with your sleep position—lower for stomach, medium for back, taller for side—to keep pressure evenly distributed. Combine posture tweaks with firmness fixes so you’re not chasing a moving target.

If you’ve tried these fixes and still wake sore, or if impressions exceed the warranty limit, shop for a firm or medium-firm upgrade. Use our firm and lumbar guides to shortlist replacements, and schedule the purchase around major Amazon sales so you can recycle the old bed without financial stress.