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March 4, 2022

Which Mattress Coil System is Right for You?

Eclipse Mattress in Bedroom Setting

The innerspring mattress was named after the metal coils or springs that form the support core of your mattress and dates back as early as the 1800s. They are time-tested and a majority of mattresses sold today still have some kind of spring system in them.

These metal coils support the mattress and form a durable surface to sleep on. These coils are designed to flex in response to pressure and movement, providing firmer support as more pressure is placed on the mattress. The quality of an innerspring mattress depends on several components used in the construction of the mattress. The type of coil system, gauge of the coil and materials used in the comfort layer or top of the mattress all factor into the overall comfort and durability of the end product.

Coil count was once a key factor used to determine the quality of an innerspring mattress but in more recent years it was discovered that the gauge of the wire, the type of coil used, and the sleeping style of the customer are more important in determining which mattress is the right fit for you.

Coil Gauge and Construction

Icon, illustrated innerspring mattress cut away

Three factors when making a coil include wire gauge, working turns and tempering.

Wire gauge refers to the thickness of the wire used to make the coil. A range of 12 to 15 gauge determines the firmness or softness of a mattress. A thick wire has a lower gauge and provides a firmer feel. A thinner wire has a higher gauge and provides a softer feel.

The number of working turns in each coil determines how tight each wire is wound. The more turns, the tighter, firmer and more durable the coil. Fewer turns result in a lighter, springier feel.

Tempering is a cooling and heating process that ensures the shape of the coil is retained even after prolonged use. Doubling the process increases the durability of the coil and is referred to as “double heat tempering.”

Coil System

To be comfortable, a mattress must provide balanced pressure relief and spinal support. The vast majority of mattresses accomplish this by pairing a sturdy base with a softer comfort section. Among the most common materials used in the support core are mattress coils.

The core of an innerspring and of many hybrid mattresses consist of coils or metal springs that are arranged in a pattern to support the weight of the sleeper. There are several different types of coils, each of which is optimized for a different function. In addition to the Bonnell coils, offset coils, continuous-wire coils, and pocketed coils used in the support core, some mattresses also utilize smaller coils in the comfort layer or top layer of the mattress.

Understanding how the different styles of coils contribute to the feel and durability of the mattress will help you decide which mattress is best for you. Coil construction affects how the mattress feels, how long it lasts and how much it costs.

The Bonnell Coil

The Bonnell coil has an hourglass open shape with a knot at each end and is based on 19th-century buggy seat springs. This coil system is the most prevalent in the mattress industry because it is inexpensive to produce.

The Offset Coil

The offset coil also has an hourglass shape but the circles at the top and the bottom are flattened to create a hinged action within the mattress core.

This coil system allows your mattress to conform to the curves of your body and is quieter than the Bonnell system.

Offset coils are generally found in more expensive innerspring mattresses.

Continuous Coils

Continuous coils are made from a single wire formed into S-shaped ringlets. Each spring is attached to each other creating a firm and stable mattress core but also can cause a squeaking sound due to the coils rubbing against each other after extended use. Continuous coil mattresses also have an increased coil count but does not make it a higher quality mattress. This is one reason coil count has become an unreliable way to judge the quality of a mattress by one factor alone. Continuous coil mattresses are durable but don’t give the same support as other coil systems. Continuous coils are generally found in lower-end, inexpensive mattresses.

Pocketed Coils

Pocketed coils are coils individually wrapped in fabric pockets to isolate motion transfer which makes them superior to all other coil mattresses but also cost more. These fabric pockets allow each spring to move alone without causing the typical “domino” effect of other coil systems. Pocketed coils are found in most hybrid mattresses and higher-end mattresses.

Micro Coils

Micro coils are unlike any other coil and are found in the comfort layer of a mattress not the support layer. These coils create a flexible surface that is either glued, sewn or welded into the comfort layer. These coils range from 1” to 3” and are made with higher gauge wire for a lighter feel. Micro coils conform to the contour of your body, isolate movement and provide a good level of overall responsiveness.

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Comfort Layer

The comfort layer of a mattress contributes to the overall feel of the mattress. These layers slightly conform to your body, providing a cushion between you and the firmer support layer beneath.

The simplest, least expensive innerspring mattresses as well as firmer style mattresses consist mainly of the coil support core with a thin foam cushion or two for the comfort layer.

Higher-end mattresses can have a multitude of materials in the comfort layer of the mattress to provide a luxurious feel. Hybrid mattresses tend to have a comfort layer equal or larger than its support core and provide a larger comfort surface than the original innerspring style.

The Benefits of Buying an Innerspring Mattress

Innerspring mattresses date back centuries, they are the most cost-effective and are still the most common mattress sold.

The spring core of an innerspring mattress provides excellent air flow, breathability and a responsive bounce that is not found in a foam mattress.

The steel construction provides proper spinal alignment, edge support and durability. Innerspring mattresses also tend to be more lightweight than foam and latex beds making them easier to rotate and maneuver.

More importantly, innerspring mattresses are available for all types of sleepers. Even sleepers that tend to switch positions throughout the night benefit from the springy surface making it easier to move across the mattress.

Side Sleepers

Photo: Woman sleeping on bed with lavender back drop Side sleeping is the most common sleeping position. Side sleepers tend to prefer a softer, or more plush innerspring mattress with pocketed coils that contour to the shape of their body and relieve the pressure points created by the shoulders and hips. Sleeping on your side naturally reduces back pain, improves breathing and promotes better digestion.

Mattress Express innerspring mattress favorites for side sleepers include our Eclipse Cosmopolitan, Eclipse Deville, or Purple Hybrid Premier 4.

Back Sleepers

Back sleepers do best on a medium-firm innerspring mattress with pocketed coils, though you can find comfort on a wide range of firmnesses. The most important consideration for a back sleeper is proper lumbar support so your hips don’t sink too deeply.

Mattress Express innerspring mattress favorites for back sleepers include our Eclipse Lido, Purple Hybrid Premier 3 and IFS Black Glacier Hybrid.

Stomach Sleepers

Stomach sleeping is generally considered the least healthy position, but stomach sleepers can be comfortable with the right firmness level. Choose a medium to firm mattress with pocketed coils to keep your spine in its natural alignment and to prevent your hips from sinking too far into the mattress.

Mattress Express innerspring mattress favorites for stomach sleepers include our Eclipse Astral, Purple Premier Hybrid and Body Fit Savannah.

To find the innerspring mattress that works for you, visit your local Mattress Express or browse your options in our online shop.