A Glossary of Mattress Terms

The mattress world of mattresses is kind of a mess.

There’s the producers, these mattress companies, with their heads full of all these ideas about how to improve your sleep—all the latest and greatest technologies, materials and construction techniques that come together to make any kind of mattress you could possibly dream of.

And then there’s you, the consumer, who probably just wants a decent mattress that’s not going to give you too much trouble.

You start off with that idea in your head, but the more you start researching your next mattress purchase, the more confusing it all seems to get.

There’s a specialized term for everything, but no mattress company seems to have a place where they actually sit down and define it all!

If you’re feeling a little overwhelmed right now, this guide is for you.

We’ve put together a complete glossary of just about any term you’re likely to come into, so you can shop with confidence.



Adjustable Bed: A bed built with adjustable motors that can change the angle of your sleeping body, allowing you to get in the most comfortable position possible

Airbed: A bed built with various motors that pump air into mattress bladders, allowing you to adjust the firmness level of your mattress

Avena Foam: An alternative to natural latex, designed to mimic its properties while increasing durability


Bed in a Box: A mattress ordered online and delivered in a box

Bed Sore: A painful, tender area of the skin caused by lying in bed too long with too little movement. Typically found in people who are bedridden or wheelchair-bound

Blended Latex: A combination of natural and synthetic latex

Bonnell Coils: The most common type of mattress spring, coiled in a characteristic hourglass shape that allows for both flexibility and support. The cheapest, least durable type of coil

Bonnell Units: Bonnell coils laced together at cross wire helicals

Border Rod: A sturdy wire running around the perimeter of a box spring

Bounce: The degree to which a mattress pushes back in response to pressure

Box Spring: A spring-filled base that goes underneath a mattress, decreasing wear and tear on the mattress

Buckling Column Gel: A well-ventilated polymer used in certain mattresses and mattress toppers, providing a high degree of both comfort and support


California King: The largest mattress size, clocking in at 72” x 84”

Circadian Rhythm: Your 24-hour inner clock that makes you feel tired at night and alert in the morning

Closed Cell Foam: Foam made with cell walls totally disconnected from each other, providing a denser structure with higher compressive strength

Coil: Curved pieces of high-density steel wire that compress and expand depending on where pressure is placed

Coil Count: The number of coils in a mattress

Coil Density: The number of coils in a mattress per square foot

Coil Gauge: The thickness of the wires that make up a coil. For every one-digit increase in gauge number, thickness increases by 10%. So, the higher the gauge, the thinner the wire

Comfort Layer: The cushioning levels of padding on top of an innerspring mattress’s support core

Continuous coils: Coils made up of a single length of S-shaped wire, allowing a mattress’s entire spring system to function as a single unit. Provides good stability and support, but poor motion isolation

Contouring: The amount a mattress conforms in response to the shape of your body


Damask: See ticking

Daybed: A couch that can become a sofa in the daytime and a bed at night

Differential Construction: A comfort layer building technique that strongly differentiates between the upper and lower support layers, with the upper layers providing both give and support, and the lower layers preventing your body from sinking too low into the mattress

Double: The second-smallest mattress size, measuring 53” x 75”

Dunlop: The simpler of the two latex mattress production techniques. Latex is poured into a mold, fired up, cleaned and dried, and presto! New mattress.

Durability: The length of time a mattress can be expected to remain at peak performance with proper care


Edge Guard: Foam padding surrounding the perimeter of a mattress, preventing mattress sagging

Edge Support: See edge guard

Edge Stabilization: See edge guard

Egg Crate Foam: A soft foam covered in up-raised bumps, resembling the underside of egg cartons. Frequently used a mattress topper

Elasticity: A material’s ability to return to its initial shape after pressure is removed

Electric Bed: See adjustable bed

Encased Springs: See pocket coils

Encasement: An air-tight sleeve that covers a mattress, protecting it from spills and stains

Euro Top: An additional padding layer sewn into the top of a mattress, sleeker and more firmly attached than pillow tops


Firm: The feel of a mattress with less give (though not necessarily more support)

Firmness: The subjective, relative experience of a mattress’s give under your body

Foundation: A wooden, slatted, fabric-covered frame. Similar to a box spring, but designed only to support your mattress

Full: See double

Futon: A fabric sack filled with padding that can be used as either a sofa or a mattress


Gauge: See coil gauge

Give: The amount a mattress compresses in response to weight


Hand Feel: The tactile sensation of a mattress under your hand

Heatiness: The amount a mattress traps in heat

Helical Lacing: Wires connecting mattress coils together

Hug: See sinkage

Hybrid Mattress: An innerspring mattress with a thick layer of memory foam or latex padding on top

Hypoallergenic: Refers to a mattress that does not accumulate allergens over time


Indentation Load Deflection (ILD): A measure of memory foam firmness, calculated by the amount of pressure it takes to indent a four-inch thick piece of memory foam by 25% across 50 square inches

Indentation Force Deflection (IFD): The metric version of Indentation Load Deflection, identical in every way except the units used to measure it

Innerspring: The most common variety of mattress, consisting of a coil core on the bottom and comfort layers on top

Insulator: The bottommost comfort layer, separating the innerspring from the rest of the mattress


King: The second-largest mattress size, coming in at 76” x 80”


Latex Mattress: A better-ventilated, more expensive alternative to a memory foam mattress made either chemically or from the sap of the rubber tree

Law Tag: A piece of paper on the bottom of all mattresses reading “Do not remove this tag under penalty of law.” This statement only applies to mattress manufacturers, not consumers, but it’s considered your proof of purchase


Manufacturing Defect: A flaw in your mattress, often quite narrowly-defined in your mattress warranty. Common examples include splitting at the seams, structural failure, and extreme sinkage.

Marshall Coils: See pocket coils

Mattress Protector: See encasement

Memory Foam: The second most-common mattress type (after innerspring), consisting of a foam that sinks in response to heat and pressure, maximizing support

Microcoils: Tiny coils typically used in mattress toppers in conjunction with foam or quilting

Middle Upholstery: The largest component of a mattress’s comfort layers, designed to increase sleeper comfort

Migration: The displacement of mattress fibers over time, usually away from the area over which a person has been sleeping

Motion Isolation: A mattress’s ability to absorb movements. Particularly useful for couples in which one partner is a light sleeper and the other tends to be restless

Motion Transfer: The transfer of movement from one area of a mattress to another


No-Flip Mattress: A mattress that doesn’t require overturning every few months


Off-Gassing: The release of compounds into the air when a mattress is first taken out of the box, making it smelly for a couple days

Offset Coils: Hourglass-shaped coils with squared-off heads, linked together with bits of helical lacing that create a hinging effect in response to pressure

Open Cell Foam: Less dense and more breathable than closed-cell foam. Less vulnerable to mold growth

Organic Mattress: A mattress made with natural, non-toxic materials with fewer chemicals than a traditional mattress

Out-Gassing: See off-gassing


Pillow Top Mattress: An additional layer of padding on the surface of a mattress, making the mattress noticeably thicker and softer. The softest mattress comfort layer commonly available

Pitch: The angle of a mattress’s coils relative to the top of the mattress

Plush: Soft

Pocket Coils: Individually wrapped coils, each of which interacts with your body individually. This allows for a more feel and minimizes motion transfer.

Polyfoam: The cheapest, lowest-quality variety of foam used in mattresses and mattress toppers, most commonly found in egg crate mattress toppers

Pounds Per Cubic Foot (PCF): A measure of memory foam density

Pressure Point: An area of the body that feels uncomfortable when lying down, caused by a pinching of the soft tissues between the mattress and your bones. These are signs of bad mattress conformity and support

Progressive Construction: A comfort layer design technique in which materials get “progressively” firmer as you sink deeper into the mattress.

Prorating: The practice of charging a given percentage of a purchase’s original cost for each year after a specified date if the buyer wishes to buy a replacement of the original purchase


Queen: The most common bed size, measuring 60” x 80”

Quilting: The topmost layer of a mattress, playing a major role in qualities like fire resistance, breathability, and temperature regulation


Recovery Time: The amount of time it takes a mattress (usually memory foam) to return to its initial shape after having been compressed

Resilience: A measure of a foam’s ability to spring back to its initial shape after having been compressed

Responsiveness: A measure of how quickly a mattress reacts to heat and pressure—that is, how long it takes the mattress to respond to the shape of your body after you’ve lain down


Sagging: The tendency for the top comfort layers of a mattress to compress inwards over time, resulting in an uncomfortable indentation on the surface of the bed. This tends to happen more quickly in cheaper mattresses than in higher-end ones

Single: See twin

Sinkage: A mattress’s tendency to “sink” beneath your body, often bringing a feeling of comfort and buoyancy. Some people may find too much sinkage uncomfortable, though, since it can also create an unpleasant “sinking” sensation

Single Coil System: See Bonnell unit

Sleeping Hot: The feeling of being uncomfortably hot when trying to get to sleep, often leading to low-quality rest. Especially common in cheap memory foam mattresses

Support: A mattress’s ability to keep up a comfortable pressure on certain parts of your body, allowing your spine to retain its natural “S” shape

Support Layer: See comfort layer


Talalay: The more involved of the two latex mattress production techniques. A mold is filled partway with latex and sealed. It’s then vacuum volumized, filling the mattress with pores. The mattress is flash frozen to -20 degrees Fahrenheit, then vulcanized, washed, and dried.

Thread Count: The number of horizontal and vertical threads in a square inch of fabric. Important when buying sheets—the higher the thread count, the softer the sheet

Ticking: The fabric that encases the outside of a mattress, protecting the materials and maintaining the shape of the mattress

Tight Top: A mattress with no pillow-like padding on its topmost layer, instead relying on a thick layer of upholstery

Topper: An extra layer of padding that can be placed on top of a mattress, often significantly improving the mattress’s comfort and feel

Trial Period: A space of time during which a mattress can be returned either for free or for a small fee. Typically around 100 days at most online mattress companies, and between a few days and a few weeks at most brick-and-mortar stores

Twin: The smallest mattress size, usually only suitable for one adult. 38” x 75”.


Ultra Soft: A mattress with an extreme amount of give and often little support. Usually between a 2 and a 3 on the 1-10 firmness scale.

Uncoil System: See Bonnell unit

Universal Comfort Mattress: A mattress that fits the firmness needs of almost every sleeper. Almost always somewhere between a 5 and a 7 on the 1-10 firmness scale. If a mattress company is advertising “universal comfort,” that means they only sell mattresses at one firmness level

Upholstery Layers: See comfort layers

Upward Thrust: See support


Viscoelastic: The main component of memory foam. Viscoelastic materials soften in response to heat, which is why it takes memory foam a couple seconds to adjust to your shape


Warranty: A guarantee that a mattress company will replace your mattress if found defective within a stated amount of time. Often less comprehensive than you might think, since “defective” usually only covers manufacturing flaws. It’s usually very difficult to get a mattress replaced under warranty.

Waterbed: A mattress relying on water for support, rather than an innerspring or foam system.

White Glove Delivery: Usually applies non bed-in-a-box online mattress purchases. A crew comes to set up your mattress wherever you want it, so you don’t have to lug it around your house yourself

Wrapped Coils: See pocket coils


Zoned Construction: A comfort layer design technique in which the firmness of the mattress’s materials varies based on what part of your body they’re likely to come in contact with. (Different areas of your body require different levels of support.) Incorrect zoning often does more harm than good, so be wary of these mattresses