Mattress Terms:
An In-Depth Glossary

Researching mattresses can introduce you to many new words and concepts, sometimes technical in nature. Some terms are used by mattress manufacturers in their marketing and product descriptions. Others are employed by experts like our testing team when reviewing mattresses. While these new terms may feel overwhelming at first, our basic glossary can help you understand what you really need to know when mattress shopping.

Whether you’re learning about mattress construction, performance, or accessories, this is your go-to resource for mattress terms. With the background knowledge we share here, you can effectively compare your options and shop with confidence. 

Mattress construction is the main driver of mattress performance. The different layers of a mattress are essential to how a mattress feels and its benefits and drawbacks. These terms are commonly used to describe elements of a mattress’ construction.

Base Layer: Generally, the bottom layer of a mattress, though sometimes there is a very thin stabilizing layer beneath it. The base layer forms all or part of the mattress’ support core, which gives structural integrity and stability to the mattress. Base layers can be made of innersprings, pocketed coils, latex, polyfoam, or air chambers. The materials that make up a mattress’ base layer determine what type of mattress it is.

Comfort Layer: A layer that rests above the support core in the topmost part of the mattress. Comfort layers directly impact cushioning, support, and other aspects of performance. Foam and latex are commonly used in comfort layers. Some mattresses contain only one comfort layer, while others use multiple comfort layers that collectively can be called a “comfort system.” 

Cover: The material that forms the exterior of the mattress. Most mattress covers are made with a fabric like cotton or polyester. In some models, the cover has a zipper so that it can be removed and washed.

Density: A material’s weight divided by its volume. In mattresses, high-density materials tend to have a firmer feel. They are also usually sturdier and more stable. 

Durability: How long a mattress lasts. Over time, mattresses tend to soften or sag from regular use. Mattresses that resist this wear and tear are more durable and can be used for a longer period of time.

Euro-Top: An added layer of material sewn onto the top of a mattress that sits flush with the rest of the mattress for a sleek and compact look. Also known as a Euro-style pillow-top, a Euro-top is often denser than other pillow-tops and may be made of materials like foam, cotton, or wool. 

Fire Barrier: A component designed to make the mattress compliant with federal product safety guidelines. A fire barrier can be a chemical treatment or a fire-resistant material like wool that makes it harder for flames to spread through the mattress layers.

Mattress Core: A synonym for support core and way of collectively describing the bottom layers of a mattress that serve as its base of stability and support. Metal coils and high-density polyfoam are the most common materials found in a mattress core, but air chambers and latex are used in some models.

Mattress Profile: The height of a mattress. The mattress profile affects how easily you can get in and out of bed. Certain setups, like bunk beds, trundle beds, and RV beds, may require lower profiles. Also, taller profiles can require fitted sheets with deeper pockets. 

Natural Fibers: A textile fiber derived from a plant or animal source. The most common natural fibers in mattresses are cotton and wool, which are often used in the mattress cover.

Pillow-Top: An additional layer tufted onto the top of a mattress. While sewn in place, it is visibly distinct from the rest of the mattress. Most pillow-tops use foam, latex, or quilted fabric to add comfort to the mattress. 

Polybrominated Diphenyl Ethers (PBDEs): A type of chemical that reduces the risk of something catching on fire. These chemicals are known as flame retardants and are used in some mattresses and other manufactured products. 

Quilted Layer: A top layer that is sewn into the cover of the mattress. Common materials found in a quilted layer include wool, cotton, and foam. This design is generally intended to add cushioning to the mattress.

Support Core: The bottom layers of a mattress that provide a base of stability. The materials in the support core have a firmer feel with less cushioning. In most mattresses, the support core is made with metal coils, high-density polyfoam, latex, or air chambers. It may also be called the base layer or mattress core. 

Transition Layer: A layer that sits between the comfort layers and the support core. Only some mattresses have a transition layer, which is usually engineered to resist sinkage while contributing to overall pressure relief. 

Zoned Support: A way of trying to enhance spinal alignment by having different amounts of pushback and cushioning across different parts of the mattress. For example, zoned support may involve a firmer feel under the midsection and more pressure relief around the hips and shoulders. 

We use the term mattress types to categorize mattresses according to their internal materials. Each mattress type has its own set of terminology centered around its key components.

Foam Mattresses

In a foam mattress, the support core is made of foam and most or all of the comfort layers are also made with a foam material. These mattresses typically include multiple kinds of foam and may offer other design features. 

Adaptive Polyfoam: A foam material intended to cushion the body’s pressure points without deep sinkage or close contouring. It is usually included as a comfort layer to enhance support without the hug of memory foam.

Buckling Column Gel: A flexible gel material that is arranged in a grid of columns that looks like a honeycomb or large tic-tac-toe board. When weight is applied, the columns collapse down, allowing the material to cushion the body. When weight is removed, the columns spring back to their original shape, giving buckling column gels a bouncier feel than most foams. 

Convoluted Foam: Foam that is shaped to have peaks and valleys, making it look like an egg crate. This allows the foam to relieve pressure while maintaining space for airflow. 

Copper-Infused Foam: A foam with beads or threads of copper incorporated into it. This manufacturing process is designed to reduce heat buildup and limit microbial growth. 

Foam Density: A measurement of foam’s weight relative to its volume, usually listed in pounds per cubic foot (PCF). High-density foam weighs more and is usually firmer and more durable. The highest-density foams tend to be used in the mattress support core. 

Gel-Infused Foam: Foam with gel interspersed within it that is engineered to limit heat retention. Foam can be infused in various ways, including in a swirl pattern or as tiny beads inside the foam.

Indentation Load Deflection (ILD): The amount of force that has to be applied to a material in order for it to compress by a certain percentage, which is often 25%. A firm material will have a higher ILD than a soft material. ILD may also be called indentation deflection force (IDF).

Memory Foam: A type of foam, also called viscoelastic foam, engineered by NASA to conform to and support the body. It compresses proportionally to where and how much weight is applied,  then slowly retakes its shape when that weight is removed. With these properties, memory foam closely hugs the body to relieve pressure.

Polyurethane Foam (Polyfoam): A broad category of foam that is used in many ways in mattresses. Manufacturers can alter the properties of polyfoam to modify its firmness, density, contouring, and bounce. This allows polyfoam to be used in comfort, transition, and support layers.

Support Foam: High-density polyfoam that makes up the support core of a mattress. 

Hybrid and Innerspring Mattresses

Both hybrid and innerspring mattresses have a support core of metal coils. In a hybrid, there are multiple layers that form a comfort system above the coils. In contrast, an innerspring mattress has very little additional material on top of the coils.  

Because of their similarities, hybrid and innerspring mattresses share much of the same terminology.

Bonnell Coils: A classic type of metal coil system involving a grid of hourglass-shaped coils that are interconnected. While more affordable than many other types of coils, Bonnell coils tend to be noisier, transfer more motion, and offer less tailored pressure relief.

Coil Count: The total number of coils in the coil layer of a mattress. The coil count alone can’t tell you much about the quality or performance of an innerspring layer, because it doesn’t account for the thickness, quality, or structure of the coils. 

Coil Gauge: The thickness of the coils, usually measured with numbers ranging from 13 to 17. Although counterintuitive, a higher gauge means a thinner coil. Thinner coils tend to give a softer feel. Some mattresses use more than one gauge of coil. For example, they may use one gauge throughout the support core, then another to reinforce the perimeter. 

Coil-on-Coil: A type of mattress construction with multiple layers of coils. In most cases, at least one of these layers is made with microcoils, which are not as tall as coils that are normally found in the support core. 

Continuous Coils: A type of coil construction that involves an arrangement of metal coils that are all formed out of a single wire. This structure creates more durability and firmness, but continuous coils can cause significant motion transfer and noise.

Microcoils: Coils that are much shorter than traditional innerspring coils and sometimes called minicoils. In most cases, microcoils are only 1, 2, or 3 inches tall. Microcoils are typically designed to form a transition or comfort layer instead of a base layer. 

Nanocoils: The smallest of microcoils, which are engineered to have a low profile for use as a comfort layer. Nanocoils usually measure an inch or shorter.

Offset Coils: Coils that have the form of an hourglass but with a square-shaped top that gives them an ability to hinge and bend in conjunction with the surrounding coils. Compared to Bonnell coils, offset coils provide more tailored support and less motion transfer. 

Pocketed Coils: A coil support system in which each coil is encased in fabric. The fabric pieces are then connected to each other, allowing the coils themselves more freedom of movement. As a result, pocketed coils offer the best contouring and motion transfer of any innerspring design. They are also known as wrapped coils. 

Latex Mattresses

In most latex mattresses, all of the layers are made of this rubber material. A latex mattress may contain one thick piece of latex or several different latex layers. 

Blended Latex: Latex made with a mix of natural latex and synthetic latex. The proportion of each type is usually indicated on the mattress label.

Dunlop Latex: Natural latex manufactured with the Dunlop process. After the latex sap is extracted from trees, it is frothed to add air, placed in a mold, and then baked. Dunlop latex tends to be dense and bouncy. It can be used in any component of a mattress.

Natural Latex: Latex derived from the liquid sap that comes from rubber trees. Some curing agents are used in the manufacturing process, but 95% of the final product is usually latex sap. 

Organic Latex: Latex made according to standards for organic production. In the mattress industry, the most common certification for organic latex is called the Global Organic Latex Standard (GOLS). GOLS-certified latex must be at least 95% certified organic latex by weight.

Synthetic Latex: Latex derived from a chemical process using petroleum instead of sap from rubber trees. Its more technical name is styrene-butadiene rubber (SBR). Synthetic latex is less expensive, but offers less durability and performance than natural latex, making it less frequently used in mattresses.

Talalay Latex: Natural latex made with the Talalay process. Using this method, latex sap is frothed, put in a mold, vacuum-sealed, then rapidly frozen before being baked. This gives Talalay latex an airier structure with plenty of bounce and cushioning that makes it well-suited for comfort layers.

When choosing a mattress, you want to look for one that suits your individual needs. Knowing the basics about different elements of mattress performance can help you find the best mattress in your situation.

Body Impressions: Indentations in the mattress surface that don’t go away when you get out of bed. Over years of nightly use, it’s normal for a mattress to develop some small body impressions. Deep impressions or sagging can be a sign that a mattress needs to be replaced.

Bounce: A feeling of springiness when you move on a mattress surface. This happens when the material quickly rebounds to its original shape after weight is removed from it. Bounce makes it easier to move in bed, including during sex, but also contributes to motion transfer across the mattress. 

Breathability: A way of describing whether air can move freely through a material. Ventilating airflow enables more rapid cooling and evaporation of moisture.

Comfort: A subjective element of mattress performance relating to your ability to feel relaxed and at-ease when lying in bed. The main factors determining your comfort include firmness, pressure relief, temperature regulation, and spinal support.

Conforming: How much a mattress contours to or hugs your body. Contouring can increase pressure relief, but too much hug or sink may be uncomfortable for some sleepers.

Contouring: Another term for conforming that relates to how much a mattress molds around the shape of your body.

Deep Compression Support: How well a mattress can provide stable cushioning to heavier parts of the body. A mattress with deep compression support won’t sag excessively or “bottom out” under the shoulders or hips. 

Ease of Movement: How much the mattress permits you to move without obstruction, including when switching between sleep positions or having sex. Contouring tends to make it harder to move on the mattress surface. In contrast, bounce enables more freedom of movement. 

Edge Support: How stable the mattress feels around the perimeter. Strong edge support makes it easier to get in and out of bed. Edge support also allows you to lie down or sit on the edge of the bed without the mattress giving out underneath you.

Firmness: How soft or hard a mattress feels. We use the same scale of 1 to 10 (with 1 being the softest) for all mattresses that we evaluate. Finding the right firmness level is important to both comfort and support. 

Motion Isolation: The ability of a mattress to absorb movement, so it doesn’t travel across the surface of the bed. Motion isolation helps prevent bed partners from disturbing each other during the night. Bouncy materials usually transfer more motion than materials with lots of contouring. 

Off-Gassing: The release of volatile organic compounds (VOCs) produced during the mattress manufacturing process. Off-gassing is what causes a “new mattress smell.” Off-gassing is typically worse with foam materials.

Point Elasticity: How much a mattress compresses in the specific spots where weight is applied. When a material has high point elasticity, it can hug the body because the material only compresses in places where the body is pressing against it. Memory foam is widely regarded as the material with the best point elasticity.

Pressure Relief: The ability to cushion the body and prevent harsh impact with the mattress surface. Strong pressure relief can reduce stress around potential pain points like the knees, hips, and shoulders. By supporting key areas of the body, pressure relief also contributes to better spinal alignment. 

Responsiveness: How bouncy or springy a mattress feels. Responsiveness facilitates ease of movement and sexual activity but can cause motion transfer. Latex and coils are among the most responsive mattress materials.

Sex: How effectively a mattress facilitates an active sex life. This encompasses the bed’s firmness, ease of movement, edge support, and temperature regulation, all of which can influence a bed’s suitability during intimate moments. 

Sinkage: The degree to which a mattress compresses under the body. While some sinkage is normal when weight is applied, excessive sinkage often leads to discomfort and spinal misalignment.

Spinal Alignment: How well your spine stays in a neutral position without excess bending or twisting. To limit aches and pains, a mattress should promote a posture that accommodates the natural curve of the spine. 

Support: The effectiveness of a mattress in keeping the body in a posture with proper spinal alignment. In practice, support requires a balance of stability and pressure relief. This ensures that the body’s heaviest areas get enough cushioning without excessive sinkage that pulls the spine out of line.

Support Factor: A way of measuring the force needed to compress certain materials, such as foam or latex. A high support factor usually means more density and firmness, but few mattress companies publish data about the support factor of their materials.

Temperature Control: The degree to which a mattress can maintain a neutral surface temperature. In most cases, this means that a mattress resists heat buildup that can cause you to sleep hot. Breathability also influences temperature regulation.

Volatile Organic Compounds (VOCs): Tiny particles that are created during the mattress manufacturing process that can be released when a new mattress is unpackaged. VOCs can briefly cause a noticeable odor.

When shopping around for a mattress, you may encounter different product labels and certifications. Each is based on specific technical criteria, but knowing the basics can help you find a mattress that aligns with your preferences. 

CertiPUR-US: A U.S.-based program that certifies healthier foam materials. CertiPUR-US foams are free from a defined list of compounds that are known to be harmful, including some heavy metals and flame retardants.

Certified Organic: An indication that the processes used to make a material comply with standards of organic production. Different organizations have their own criteria, but in most cases, organic certification prohibits or greatly limits the use of synthetic additives or chemicals. 

eco-INSTITUT: An international organization that certifies products that have been demonstrated to emit only low levels of VOCs.

Global Organic Latex Standard (GOLS): A well-regarded certification program for latex materials. The GOLS program involves an assessment of how latex materials are sourced. It also evaluates the environmental and social impacts of latex production. 

Global Organic Textile Standard (GOTS): A major organic certification program for different kinds of fabrics, including wool and cotton. As with the GOLS program, the GOTS certification requires third-party analysis of a textile’s sourcing and its impact on the environment and workers.

GREENGUARD: A program to certify that materials have low levels of off-gassing. There are different levels of GREENGUARD certification, including GREENGUARD Gold, which requires more rigorous testing and documentation.

OEKO-TEX Standard 100: A certification that focuses on 100 specific dangerous compounds that can be found in textiles. Materials with the OEKO-TEX 100 certification have shown that they do not contain or emit these compounds.

Rainforest Alliance: A certification program centered on how a material impacts tropical rainforests. To receive Rainforest Alliance certification, manufacturers have to demonstrate that they meet specific standards for social and environmental protection.

Sustainable Furnishings Council: An industry organization with a mission to promote environmentally conscious practices in home products, including mattresses. There is currently no third-party certification or auditing involved for companies that are part of the Sustainable Furnishings Council.

Different services may be offered when you buy a new mattress, and understanding some key terminology can enable you to get the most out of your purchase.

Break-In Period: The time that it takes for your body to adjust to a new mattress. In most cases, it ranges from a few days to a few weeks. To account for this break-in period, some manufacturers require you to try a mattress for 30 nights before making a return. 

Old Mattress Removal: Haul-away of your existing mattress. Some mattress companies offer old mattress removal as part of White Glove delivery. This service may also be available from third-party organizations in your local area.

Mattress-in-a-Box: A mattress that has been compressed, rolled up, and tightly sealed in plastic before being placed in a box. This packaging process makes it easier for mattresses to be shipped directly to your home. When the mattress is unboxed, it decompresses and regains its normal size.

Sleep Trial: A period when you can try a mattress in your home with the option to return it if you aren’t happy with its performance. You will usually have a sleep trial of 100 nights or more if you buy online. Most manufacturers do not charge return shipping if you decide to return a mattress during the sleep trial, but some have a return fee.

Warranty: A type of consumer protection that obligates the manufacturer to repair or replace a defective mattress. While a warranty gives you a remedy if there’s something clearly wrong with how the mattress was made, it almost never covers normal wear and tear.

White Glove Delivery: A service to install a mattress in the room of your choice and get rid of any packaging materials. In most cases, White Glove delivery also includes haul-away of an old mattress. 

Various items can enhance your sleep setup, and these fall into the category of mattress accessories. Accessories can range from “must-haves” to “nice-to-haves,” so it’s important to be aware of the different types available for your bedroom. 

Adjustable Base: A mattress frame that has the ability to raise and lower the head and/or foot of the bed. Using an adjustable base requires a compatible mattress that won’t be damaged when the frame moves. An adjustable base can contribute to comfort and relief for certain health issues.

Base: A piece of furniture that the mattress rests on. It is also known as a foundation. There are various types of mattress bases, including frames, adjustable bases, and platform beds.

Bed Frame: A basic structure that provides space between your mattress and the floor. Most bed frames are rectangular, have four to six legs, and are made of either wood or metal. A frame can support a mattress alone or a mattress and a boxspring.

Boxspring: A type of mattress base with metal coils inside a rectangular wood structure. Putting your mattress on a box spring raises the height of your bed and can add stability and bounce to its overall feel.

Mattress Encasement: A fabric material that completely covers your mattress. Most encasements have a zipper to fully seal the mattress inside. They are often waterproof and designed to keep spills, dust, bed bugs, and allergens away from your mattress.

Mattress Pad: A thin layer of material that goes on top of the mattress surface. A pad can be held in place like a fitted sheet or with elastic straps around each corner. A mattress pad adds a touch of softness and mattress protection, but most do not fundamentally change how your mattress feels.

Mattress Protector: A product that goes on your mattress like a fitted sheet and is designed to reduce the risk of your mattress being damaged by spills or contaminated by dirt and allergens.

Mattress Topper: An added layer for the top of your mattress that can change its firmness or performance. Most toppers are 1 to 4 inches in thickness. They are frequently made of foam, latex, or a textile material like cotton or wool.

Murphy Bed: A tall piece of furniture that holds your mattress upright, usually against a wall, when not in use. A Murphy bed often looks like a cabinet or wardrobe and allows you to reduce the amount of floor space that a bed takes up. This type of hide-a-bed is popular for guest bedrooms.

Platform Bed: A type of raised base for a mattress. Many platform beds use wooden slats to support the mattress, but they may have a single piece of material for the mattress to rest upon. Platform beds come at different heights and are popular among people who want a simple and modern design for their bedroom. 

Not all mattress terminology fits into a clear category, but there are some additional words that you may come across in your mattress research. 

Alaskan King: A mattress with square dimensions of 108 inches by 108 inches. Considered an oversized mattress, the Alaskan king is only offered by some manufacturers, and it is especially useful for very tall sleepers.

Alberta King: A mattress with square dimensions of 96 inches by 96 inches. Although it is also oversized, an Alberta king is not as long or as wide as an Alaskan king. It may be called an Alaskan king mini or a Vermont king.

California King: A standard mattress size with dimensions of 72 inches wide by 84 inches long. As the longest of the standard sizes, the California king appeals to many tall people but requires sacrificing 4 inches of width compared to a standard king. 

California Queen: A mattress that is 60 inches wide by 84 inches long. This is not a standard mattress size. It provides 4 inches of extra length compared to a normal queen. 

Family Size: An oversized mattress with dimensions of 120 inches by 80 inches. With its increased width, the family size mattress is meant for couples who often have a child or pet joining them in bed.

Family XL: An oversized mattress with considerable length and width. When available, it usually has dimensions of 144 inches by 84 inches.

Flippable: The ability of a mattress to be used on either side. A flippable mattress may have the same feel on both sides, and flipping is meant to extend the lifespan of the mattress. In other cases, a flippable mattress has different firmness levels on each side, letting you choose which you prefer.

Hypoallergenic: Designed to reduce the risk of causing an allergic reaction. A mattress itself or specific materials, especially in the mattress cover, may be advertised as hypoallergenic. Some products, like mattress encasements, may also be engineered to reduce exposure to allergens.

Split Bed: A sleep setup in which there are different characteristics for each side of the bed. For example, a split bed can have distinct firmness levels on each side. Some split beds are also designed for use with a split adjustable base, letting both sleepers modify their body’s positioning to their liking. 

Texas King: An uncommon bed size with dimensions of 80 inches by 98 inches. It is one of the longest types of bed sizes, making it appealing for tall sleepers.

Value: An evaluation of your return on investment when buying a mattress. Value is determined by the quality of a mattress, how much it meets your needs, and how much you paid for it. Discounts and sales can help you get more value from your purchase.

Vermont King: Another uncommon square king size bed, with measurements of 96 inches by 96 inches. The Vermont king is another name for the Alberta king and it can also be called the Alaskan king mini.

Wyoming King: A square mattress size with dimensions of 84 inches by 84 inches. Although uncommon, the Wyoming king suits people who want the length of a California king without sacrificing width.