Finding the best mattress is like looking for a needle in a haystack.
Sorting through features for dozens of models and deciphering the technical jargon is challenging, but the good news is — it doesn’t have to be.
Our expert team put together this glossary of mattress terms to help make your shopping easier — especially if it’s been a while since you’ve shopped for a bed. Let it be your guide.
Types of Foam In Mattresses
Polyurethane foam is the general term for any foam made with polyol and diisocyanate, including memory foam, as well as proprietary blends that may contain additional ingredients. Polyfoam is the comfort layer found in most padded furniture, such as sofas and chairs. It’s resilient — press on it, and it bounces back to its original shape immediately. You’ll find it in high-density mattress bases as well as mid-density transitional layers.
Developed for NASA in 1966, memory foam is polyurethane foam that’s been chemically enhanced to increase its density and lower its resiliency. Also known as viscoelastic foam, it’s soft and conforms to the body when warmed, but once compressed, it takes longer to return to its initial shape. It’s most commonly used as a pressure-relieving comfort layer over coils or a high-density foam base.
Latex foam comes in two varieties — natural and synthetic. Natural latex is made from the milk of rubber trees, and it comes in two types — Dunlop — the dense latex found in mattresses —and Talalay — a lighter style more popular in pillows. Synthetic latex is made in a laboratory, but it has similar properties. It’s as comfortable and durable as natural varieties and may be less costly. And since it contains no natural latex, it’s an excellent alternative for people with a latex allergy.
Coil mattresses support the body with springs. Springs come in two popular styles — continuous and Bonnell. Continuous springs are wound from a single strand of steel that runs the length and breadth of the mattress — they move together. Bonnell coils are individual, hourglass-shaped springs bound together by a wire to a metal frame. They move separately, limiting motion transfer.
A foam’s density refers to how much it weighs. Measured in pounds per cubic foot, high-density varieties are firm and durable, making them ideal for mattress bases. Low-density foams are softer and used as comfort layers. Mattresses with multi-layer designs capture the unique properties of each, fine-tuning comfort and optimizing durability.
Nothing beats the comfort of memory foam, but its closed-cell structure traps heat. Infusing memory foam with gel helps regulate temperature by redistributing body warmth to surrounding materials — giving the bed a cooler overall feel.
A hybrid mattress combines the best features of features an innerspring mattress — a coil base for durability and support — with thick layers of curve-conforming foam on top for pressure relief. It’s a good compromise for couples with different comfort preferences.
We have reviewed the best hybrid mattresses under $500, if you are looking for this type of mattress.
“Innerspring” is another term for coil. Innersprings are found in conventional spring mattresses and hybrids. Most are made of sturdy but flexible heavy-gauge steel.
Pocketed coils are independent springs encased in fabric for durability and sound control. Each responds independently to movement, offering targeted pressure relief and motion isolation.
From plush to extra-firm, a mattress’s firmness reflects how much it yields to the body. Not to be confused with support, it’s the general feel of a bed and whether it resists or sinks under weight.
The firmness of foam layers is reflected by the indentation load deflection or ILD rating. ILD is the amount of weight it takes to compress a 4-inch piece of foam by 25%. The higher the number, the firmer the foam. Sleep professionals recommend medium firmness for most adults. Plus-sized sleepers benefit from a firmer bed.
Edge support is the stability you feel when you sit on the side of a bed. Foam mattresses offer the least — hybrids and conventional innerspring models provide the most. Hybrids with coils extending to the edge of the bed are firmest — styles swapping the outer rows of springs with high-density foam offer only medium support. Your choice is a matter of personal preference, but edges that are too soft to sit on safely may be a hazard for seniors or people with mobility challenges.
Thickness is the smallest of the three mattress dimensions — from top to bottom vertically as it sits on a frame. Experts recommended a thickness of at least 10 inches for adults for adequate support — more for a plus-size sleeper. Today’s adjustable bases work with most foam mattresses or hybrids less than 14 inches thick, but check the manufacturer’s specifications. For trundle beds, consider 6- and 8-inch options.
Motion transfer refers to the movement of kinetic energy from one side of a mattress to the other. Materials that better absorb kinetic energy, such as memory foam and pocketed coils, isolate motion, so when one partner moves, it doesn’t disturb the other. Old-school innerspring mattresses made with continuous coils transfer motion the most.
A supportive mattress is one that keeps that body in a neutral position. Beds that are too soft or too firm exaggerate the natural curvature of the spine in the neck and lower back, causing stress on joints and muscles. Firmness, density and thickness all play important roles in support.
Foam mattresses are made with petrochemicals and wrapped immediately after they’re manufactured. When they’re unwrapped, volatile organic compounds trapped under the plastic escape — causing a chemical odor known as off-gassing.
While it’s usually harmless, off-gassing can cause mild respiratory irritation in sensitive persons. Letting the mattress expand in a well-ventilated room for 24-48 hours typically resolves most heavy odors, but light smells may linger up to a few months. All-foam beds off-gas the most, but buyers should also expect some from hybrids. It does not reflect the quality of the mattress.
Few beds undergo rigorous testing to see how well they perform for plus-size sleepers. But some mattress materials are inherently less supportive and durable than others under heavy weight, so some manufacturers set maximum weight limits for their products.
Weight limits may be noted per side or for the entire mattress, and they can help buyers identify which beds are more or less likely to perform as expected. Exceeding the maximum capacity, however, may void the warranty.
A back sleeper lies in the supine position – facing toward the ceiling with their arms above their head or at their side. Medium to medium-firm mattresses that support the spine without exaggerating its natural curves are ideal for back sleepers.
Combination sleepers switch positions throughout the night. Most, however, have a preferred posture — one they spend more time in than others. Choose the mattress that’s the best fit for that position.
Side sleepers lay on either their left or right side. Variations of this posture include the fetal position, the most popular among women. A mattress with medium sink relieves pressure at the hips, shoulders and knees.
Side sleepers often complain of shoulder pain, which is why we have reviewed the best mattresses for side sleepers with shoulder pain.
Stomach sleepers lay on their abdomen with their arms to the side or above their head. It’s the least common sleep posture and the one most associated with aches and pains. A medium-firm to firm mattress is recommended.
Stomach sleepers, Rejoice! We have reviewed the best mattresses for stomach sleepers on our blog.
Mattress / Bed Features
An adjustable base is similar to a hospital bed — the head and feet can be raised and lowered via remote control. While each manufacturer has unique specifications, most foam and hybrid mattresses less than 14-inches thick are compatible. Conventional innerspring beds are too rigid for adjustable bases.
Allergen resistance reflects how well mattress materials repel allergens such as dust mites. Memory foam and latex are good choices unless you have a latex allergy — both are naturally hypoallergenic. Adding a zippered, allergen-proof cover offers extra protection.
Most mattress foam is formulated from petroleum-based ingredients known to contain toxic chemicals. The risk to health is low because beds are covered, but if you prefer a greener home, stick with a CertiPUR-US certified mattress.
CertiPUR-US is a voluntary, independent certification program open to all manufacturers. Foams are guaranteed to be:
Low VOC – fewer than 0.5 parts per million
Free of formaldehyde, toxic flame retardants and heavy metals, such as lead
Made without ozone-depleting chemicals or phthalates regulated by the Consumer Product Safety Commission.
Cooling features are materials or design factors that improve a mattress’s breathability and temperature regulation. Memory foam mattresses trap heat by design — it’s what makes the foam responsive — but it can be uncomfortable, especially in warm climates.
Foams with gel or graphite infusions help dissipate body heat while pin-ventilated and open-cell “airflow” foams enhance cooling air circulation. Because hybrids feature an open coil base that allows air to move through the mattress, they’re naturally cool.
Pillow tops are extra layers of comfort material layered over the top of a mattress. They come in two popular styles — conventional and euro top. Conventional pillow tops are sewn to the top of the mattress, creating a visible gap around the perimeter of the bed. Euro tops are built into the mattress. Both are equally comfortable and relieve painful pressure points; however, the padding in pillow tops is vulnerable to forming permanent body impressions — mattresses should be rotated regularly.
Trial periods are designated terms during which buyers can try a mattress for free. Research shows it takes up to three months for the body to adjust to a new bed, so manufacturers are incentivized to offer free trials — expect 30 to 100 nights. But beware — some sellers insist buyers sleep on their mattress for the full period — even if they’re certain after a few weeks that it’s not a good fit.
Warranties are written guarantees that a manufacturer will repair or replace a product for a designated period. The maker sets the terms, and from company to company, they vary significantly. In most cases, warranties cover only defects in craftsmanship, not normal wear and tear. Others are prorated — meaning buyers are reimbursed a lesser amount for defects based on the number of years they’ve owned the bed. Some warranties require purchasers to pay for return shipping — details should be confirmed in advance.
A bed is an investment in your comfort and health — it’s critical to make an informed buying decision.
So read, learn and ask questions — we hope our guide has helped. Choosing a mattress thoughtfully is the key to getting the blissful night’s sleep you deserve.