Our thickest topper
4 Inch Mattress Toppers, Extra Thick Gel Memory Foam
A 4 inch mattress topper is the deepest cushion we make, built for side sleepers, heavier sleepers, and mattresses that have lost their comfort layer. LOUNJ pours the gel-infused memory foam in our own Phoenix, AZ factory, cuts it to every standard size plus RV and custom, and ships it free.
- Made in Phoenix, AZ
- 30-Night Happiness Guarantee
- Free shipping, ships in 1 business day
Shop 4 inch toppers
All Mattress ToppersWho needs 4 inches
Most people are well served by 3 inches. Four inches earns its place in three situations. First, heavier sleepers: above about 230 pounds, a 3 inch layer compresses far enough that the shoulder and hip reach the mattress underneath, and the extra inch keeps the cushion working all night. Second, side sleepers of any weight who want a deep, enveloping feel and wake with shoulder or hip pressure on thinner toppers. Third, a mattress that has worn out on top: a packed-down pillow top, a shallow body impression, or a guest bed that is too old to replace yet.
Four inches is not the answer for stomach sleepers, who tend to sink at the hips, or for anyone who likes a firm bed. It also cannot fix a mattress that sags because the springs or core have failed; the topper will follow the dip.
What 4 inches of gel memory foam feels like
Our 4 inch Gel Mattress Topper is one uncut slab of gel-infused open-cell memory foam. At this depth the foam does all the contouring, so the bed underneath mostly disappears. You sink in slowly over the first minute and the foam holds the shape of your side profile, which is what relieves pressure at the shoulder and hip. It is the plushest feel in our lineup.
Thick memory foam has a reputation for sleeping hot and for being hard to move on. The gel infusion and open-cell structure help with the first: heat has a path out instead of collecting under you, and the foam cures in the Arizona sun so it arrives with very little odor. For the second, combination sleepers who roll often may prefer 3 inches or a responsive Talalay latex topper, which we make up to 3 inches thick.
Fit: sheets, headboard height, and bed rails
Four inches is where sheet fit becomes a real consideration. On a 10 inch mattress you now have 14 inches to cover, and on a 12 inch mattress, 16. Buy fitted sheets with pockets rated at least 2 inches deeper than mattress plus topper, or use a topper cover so the topper and mattress can be sheeted separately. Sheet straps under the mattress help too.
The sleeping surface rises 4 inches, which matters on a platform bed with a low headboard, on a bunk with a safety rail, and on a high mattress where getting in and out is already a step. Measure the rail height on a bunk before ordering; safety rails should still stand at least 5 inches above the top of the topper.
Weight, moving, and decompression
A 4 inch topper is our heaviest memory foam topper, and a queen or king is best moved by two people. Once it is on the bed it stays put; the weight and the friction of bare foam on a mattress keep it from creeping. Plan the delivery so you can unbox it on the bed rather than carrying it up stairs unrolled.
It ships compressed and rolled by FedEx Ground, free to the lower 48, and arrives in 2-3 business days. Unroll it on the bare mattress and allow the full 24-48 hours to decompress; thick foam takes longer to reach final height than thin foam. Sleep on it the first night if you like, but hold off judging the feel until day two. Our 30-Night Happiness Guarantee and 5-year warranty apply as they do to every topper.
| Size | Dimensions | Sheet pocket needed on a 10 inch mattress |
|---|---|---|
| Twin | 38 x 75 | 16 inch or deeper |
| Twin XL | 38 x 80 | 16 inch or deeper |
| Full | 54 x 75 | 16 inch or deeper |
| Full XL | 53 x 80 | 16 inch or deeper |
| Queen | 60 x 80 | 16 inch or deeper |
| King | 76 x 80 | 16 inch or deeper |
| California King | 72 x 84 | 16 inch or deeper |
| RV sizes (bare foam) | 12 sizes | Check cabinet and slide clearance |
| Custom | Up to 80 x 84 | Gel memory foam, 1 to 4 inch |
Questions about 4 inch mattress topper
Is a 4 inch mattress topper too thick?
For lighter sleepers, back sleepers, and stomach sleepers, usually yes; they will feel more sink than support. For side sleepers, sleepers over about 230 pounds, and worn mattresses, 4 inches is the right amount. If you are unsure, 3 inches is the safer middle choice.
Can a 4 inch mattress topper fix a sagging mattress?
It can smooth a shallow body impression or a packed-down pillow top, and it will make an old but structurally sound mattress much more comfortable. It cannot fix a mattress whose springs or foam core have collapsed; a thick topper follows the dip. Put a hand on the bare mattress: if the sag is deeper than about an inch and a half, plan to replace it.
What sheets fit a mattress with a 4 inch topper?
Add 4 inches to your mattress height and buy fitted sheets with pockets at least 2 inches deeper than that total. On a 10 inch mattress that means 16 inch pockets; on a 12 inch mattress, 18. A topper cover or sheet straps are a good backup if you want to keep your current sheets.
Does a 4 inch memory foam topper sleep hot?
It holds more heat than a thin topper simply because there is more foam around you. Our gel infusion and open-cell structure help a great deal, and most sleepers find it comfortable. If you are a very hot sleeper, a 3 inch Talalay latex topper or a 3 inch gel topper will run cooler.
How much does a 4 inch topper weigh?
It is our heaviest memory foam topper. A twin is a one-person job; a queen or king is easier with two people, mainly because the foam is floppy rather than because it is very heavy. Plan to unbox it on the bed so you do not have to carry it unrolled.
How long does a 4 inch topper take to expand?
Give it the full 24-48 hours. Thicker foam takes longer to recover from compression than 2 or 3 inch toppers. It will be sleepable the first night but slightly firmer and lower than its final state, so judge the feel on night two.
Do you make 4 inch toppers in RV or custom sizes?
Yes. Our bare-foam RV topper comes in 4 inch across all 12 RV sizes, and custom gel memory foam toppers can be cut up to 4 inches thick in any rectangle to 80 x 84. Check cabinet, slide, and bunk clearance before choosing 4 inches in an RV.
Deep cushion for the sleepers who need it
4 inches of gel memory foam, poured in Phoenix, shipped free, and covered by a 30-night trial.