After comparing specs, foam densities and certifications, the Tempur-Pedic TEMPUR-Topper Supreme is our overall winner for its dense, durable foam and pressure relief. For sleepers who run hot, the ViscoSoft Select High Density topper is a strong cooling-focused alternative.
A thick memory foam topper can change how an aging or too-firm mattress feels, adding deep contouring and pressure relief without the cost of a new bed. We compared the most widely sold options based on published foam density, thickness, certifications and the themes that show up across thousands of owner reviews. We do not physically test these products, so every claim here traces back to manufacturer specs or what verified owners consistently report.
Thickness matters most for heavier sleepers and for mattresses that have started to sag, since two inches or more of dense foam gives more cushion before you bottom out. Below we rank seven thick memory foam toppers across overall value, cooling, side-sleeper support and budget needs, with the trade-offs spelled out so you can match one to your situation.

This three-inch topper uses the same dense TEMPUR material found in Tempur-Pedic mattresses, which is why it leads our ranking on durability and contouring. It is slower to respond than budget foam, so it cradles joints and distributes weight evenly. The removable, washable cover adds convenience that cheaper toppers often skip.
We do not take payment for placement and we do not physically test products. Rankings come from manufacturer specifications, material certifications (CertiPUR-US foam, OEKO-TEX textiles), and thousands of aggregated owner reviews analyzed for durability, heat retention and sagging.

Sleepers who want premium, durable foam and deep pressure relief on a firm mattress · Type: 3 in memory foam | Firmness: Medium-soft | Trial: 90-night via select retailers
This three-inch topper uses the same dense TEMPUR material found in Tempur-Pedic mattresses, which is why it leads our ranking on durability and contouring. It is slower to respond than budget foam, so it cradles joints and distributes weight evenly. The removable, washable cover adds convenience that cheaper toppers often skip.
What owners report: Owners frequently report that it noticeably softens an overly firm mattress and holds its shape over years rather than developing permanent body impressions. The most common complaint is that it sleeps warm and carries a higher cost than most competitors.

Hot sleepers who still want the deep contour of thick memory foam · Type: 3 in gel memory foam | Firmness: Medium | Trial: 60-night
ViscoSoft pairs three inches of gel-infused high density memory foam with a breathable bamboo cover to help draw heat away from the body. The gel beads and ventilated structure are designed to offset the warmth memory foam is known for. A set of elastic corner straps keeps it anchored to the mattress.
What owners report: Owners say it runs cooler than standard memory foam toppers while still relieving pressure for side and back sleepers. Some note an initial off-gassing smell that fades within a few days, and a few wish the foam were firmer.
Anyone wanting maximum thickness and contouring without a premium price · Type: 4 in gel memory foam | Firmness: Soft | Trial: Varies by retailer
At a full four inches, this Lucid topper offers more cushion than almost anything in its class, making it a popular fix for sagging or rock-hard mattresses. Gel infusion helps regulate temperature, and the ventilated design improves airflow through the deep foam. The thickness gives a plush, sink-in feel that lighter sleepers tend to favor.
What owners report: Owners consistently praise how much softer it makes an old or firm bed and value the thickness for the cost. The recurring caution is that four inches of soft foam can feel too sink-in for stomach sleepers and may need a deep-pocket fitted sheet.

Side sleepers who need shoulder and hip relief with better heat handling · Type: 3 in graphite memory foam | Firmness: Plush or Firm option | Trial: 180-night
Saatva infuses this three-inch topper with graphite, a material chosen to pull heat away from the foam more effectively than gel alone. The contouring depth targets the pressure points side sleepers feel most at the shoulders and hips. An organic cotton cover with corner straps rounds out the build.
What owners report: Owners who sleep on their side report meaningful relief from shoulder and hip soreness and note the graphite helps it sleep cooler than expected. The main drawbacks cited are the higher cost and a firmer-than-anticipated feel for some buyers.

Shoppers who want a thick topper at the lowest reasonable cost · Type: 3 in gel memory foam | Firmness: Medium-soft | Trial: Varies by retailer
Linenspa delivers a genuine three inches of gel-infused memory foam at a price well below the premium field, which is why it is a go-to budget pick. The gel infusion offers modest temperature regulation, and the foam contours enough to take the edge off a firm mattress. It arrives compressed and expands over a day or two.
What owners report: Owners are generally satisfied for the cost and report it adds a noticeable layer of softness to a hard bed. Common notes include a longer expansion time and foam that is less durable over the long run than higher-density options.

Heavier sleepers and those who want supportive, not sink-in, thick foam · Type: 4 in high density memory foam | Firmness: Medium-firm | Trial: Varies by retailer
Subrtex builds this topper with four inches of higher-density foam aimed at supportive contouring rather than a plush, soft feel. The added density helps it stand up better under heavier weight without bottoming out. A breathable cover with corner straps keeps it stable through the night.
What owners report: Heavier owners appreciate that it provides cushion while still feeling supportive rather than overly soft. The most frequent complaints are noticeable off-gassing at first and a denser feel that lighter sleepers find too firm.

Sleepers who want both plush comfort and underlying support in one topper · Type: 4 in dual-layer memory foam | Firmness: Medium | Trial: Varies by retailer
This four-inch topper layers a softer comfort foam over a denser support base, giving a hybrid feel that cushions without letting you sink too far. The two-layer design aims to balance pressure relief with stability for combination sleepers. The thickness makes it a capable rescue for a worn or firm mattress.
What owners report: Owners like the balance of softness up top and support underneath, and many use it to extend the life of an older mattress. Recurring feedback points to its weight making it awkward to move and a break-in period before it reaches full loft.
Not necessarily. Three to four inches gives the deepest contouring and works best for heavier sleepers or sagging mattresses, but thick soft foam can feel too sink-in for stomach sleepers. Match the thickness and firmness to your weight and sleep position rather than buying the thickest option by default.
Memory foam traps more heat than other materials, and thicker layers can hold more of it. Gel and graphite infusions plus breathable covers help, so hot sleepers should favor toppers built with those features rather than plain foam.
CertiPUR-US is an independent certification confirming the foam is made without certain harmful chemicals and meets low-emission standards. It is a useful baseline for indoor air quality, and most reputable toppers in this guide carry it.
A three or four inch topper raises your mattress height, so standard fitted sheets may not stay on. Owners often recommend deep-pocket fitted sheets sized for the combined height of the mattress and topper.
Higher-density foam generally lasts longer, often several years, while cheaper low-density foam can develop body impressions sooner. Owner reviews suggest the denser premium options hold their shape best over time.
The Tempur-Pedic TEMPUR-Topper Supreme is our overall winner for its dense, durable foam and reliable pressure relief, making it the safest long-term choice. Hot sleepers should look to the ViscoSoft Select High Density topper for its gel and bamboo cooling features, while bargain shoppers get the most thickness for the cost from the Lucid 4 Inch Gel Memory Foam Topper. Side sleepers seeking shoulder and hip relief will be best served by the Saatva Graphite topper.