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Do More Coils Make a Better Mattress?
The Core of the Matter

Last updated on June 22, 2022

The coils, also known as the core or the innerspring unit, provide the main support for the body. Proper support is essential not only for a good night's sleep, but for maintaining a healthy spine. When considering the core of an innerspring mattress, there are a number of important factors: the number of coils used throughout the mattress, the way the coils are constructed, and the shape of the coils.

Is a High Coil Count Better?

You might have heard a rumor that the more coils in a mattress core, the more supportive the mattress will be. While this can be true, coil count is not nearly as critical today as it once was. These days the construction of the coils is a much more important factor in determining the overall comfort and support of the mattress.

  • A typical mattress contains between 250 and 1,000 coil springs
  • A mattress with a lower coil count might use thicker wire or other techniques to compensate for this (see Coil Construction below)
  • As a rule of thumb, the minimum number of coils you should look for in a mattress is 300 for a full, 375 for a queen and 450 for a king-size mattress

How are Mattress Coils Made?


When discussing the coils of an innerspring mattress, the word "gauge" refers to the thickness of the wire used to construct the coil. Somewhat counter-intuitively, the lower the number, the "heavier" the gauge, and the thicker the wire — 12.5 gauge wire (very "stiff") is thicker and stronger than 16.5 gauge wire (quite "springy").

Working Turns:

Another important factor is the number of "working turns" in each coil, a measurement of how tightly the coil is wound. Coils constructed with a higher number of working turns will result in both a softer and more durable mattress, since the work of supporting your body is spread throughout the spring. Working turns can be counted by tracing the wire with your finger — each time your finger travels 180 degrees around the coil translates to one working turn.


Tempering is the process of heating and cooling the coils to ensure they retain their proper shape over time. A "double heat tempered" coil has gone through that process twice, ensuring increased durability.

Types of Coils

There are three main coil designs used in modern mattresses: Hourglass (also called Bonnell), Pocketed and Continuous.

Hourglass Bonnell Coils

Hourglass coils, the most commonly used design, come in two varieties — Bonnell coils and offset coils. Based on 19th century buggy seat springs, the Bonnell coil has an hourglass shape with a knot at each end, and is known as the original mattress coil. Today, Bonnell coils are still the most prevalent coils in the mattress industry, though they are typically found in less expensive mattresses. The offset design, found in more expensive mattresses, is similarly hourglass shaped, but the circles at the top and bottom of each coil are flattened to create a hinging action within the mattress core. This design allows the mattress to better conform to your body, and tends to make offset coils less noisy than their Bonnell predecessors. It also allows offset coils to be connected to each other via helicals (corkscrew-shaped wires that run over the tops and bottoms of the coils), which prevents them from moving from side to side when compressed.

Below: Offset hourglass coils connected with helicals

Linenspa 6" Inner Spring

Continuous Coils

Continuous coil springs are made from a single length of wire shaped into a series of loose S-shaped ringlets. The concept behind this design is that by attaching each coil to its neighbors, the mattress core will be stronger, more stable, and more durable. Continuous coil designs also allow for significantly more coils per mattress, making it difficult to compare coil counts with non-continuous coil systems. Today, this coil type is common mainly in very inexpensive mattresses.

As with connected coils, since metal touches metal in the bed, there's potential for noise or squeaking when the coils rub against each other.

Are Pocketed Coils Better?

Pocketed coils, also known as Marshall coils, are each individually wrapped in a fabric pocket. While the pockets might be connected together, the springs are each independent of one another and can move separately. Pocketed coils provide more motion separation than other innerspring coil types, meaning that when your partner starts tossing and turning, you are less likely to be disrupted. This can really come in handy if your bed-mate is a restless sleeper. On the flip side, pocketed coils endure greater strain over time, since each coil absorbs weight without distributing it to other nearby coils.

Many innerspring mattresses now use pocketed coils, and the majority of hybrid beds use them too.

Below: Coils in their fabric pockets

King Koil World Extended Life (XL) Mattress

Micro coils

Coils are usually found in the support layer of a mattress. But coils can be part of the comfort layer, too. Micro coils are small, flexible springs that can make up a layer near the surface of a mattress. They are usually designed as individual coils wrapped in fabric pockets that are sewn, glued or welded together to create a flexible surface.

Micro coils range in height from about 1" to 3" tall. In addition to being shorter, micro coils are narrower and made with lighter gauge wire than regular coils. The lighter, encased wire gives micro coils a softer feel, and the smaller size enables more springs to be placed into a given area, also enhancing softness.

If pressure relief and motion isolation are important to you, micro coils are a good choice. They do a good job of conforming to your body’s contours. They also do a good job at isolating movement. Micro coils provide a good level of repositioning and overall responsiveness, cradling the body while creating a supportive, pressure-relieving effect for recessed areas of the body not in direct contact with the support layers of a mattress.

Spink & Co

How Long Do Innerspring Mattresses Last?

The basic techniques and materials used to make innerspring mattresses date back centuries, and are time-tested. Assuming you buy a good quality innerspring or pocketed coil mattress from a reputable brand and retailer, your new mattress should last in the neighborhood of 8 to 10 years. It could be more or less depending on your circumstances, sleep style and body weight, but a quality innerspring mattress should hold up well and resist body impressions as well as (or perhaps better than) newer-technology memory foam.

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