Definition of Coil & Coil Count

Meaning of the Term as it Pertains to Mattresses

What is a Coil?

A coil is a curved piece of high-density steel used in an innerspring mattress. Mattress manufacturers arrange hundreds of coils into tight rows and columns to create support systems. The energy-absorbing coils work in unison to support the body and distribute weight to relieve stress at pressure points.

Coils may be arranged in interconnected or independent designs. Types of coils in interconnected designs include Bonnell, offset, and continuous coils. Bonnell and offset coils are bonded or interlocked together in one system, whereas continuous coil units consist of a single, s-shaped wire. Independently moving pocket coil systems feature individually wrapped coils, which move freely in three directions.

Coil Configuration

The pattern in which coils provide support in a mattress. Coil configuration can change how a mattress feels as well as its ability to transfer motion. Some configurations may increase mattress prices.

Styles of coil configuration include Bonnell, offset, continuous wire, and encased coils. Bonnell and offset configurations provide classic mattress performance. Mattresses with continuous coils tend to keep their shape longer than mattresses with traditional coil configurations. Encased coils provide body-contouring support and reduce motion transfer.

Mattress Coil Count

The number of individual coils inside of a mattress. Higher coil counts provide better body support and increase mattress longevity. Shoppers want to avoid mattresses with low coil counts; however, minimum acceptable coil count varies by mattress size. Full mattresses need at least 300 coils, queen mattresses need 400 coils, and king mattresses require 480 coils. Shoppers should note mattresses with coil counts much greater than the minimum standards don't offer a noticeable increase in comfort or support.

Some mattresses use extra layers of padding for edge protection, which reduces the actual number of coils inside. These mattresses usually promote coil density numbers, which indicate the level of support in comparison to coil count.

When evaluating mattresses, some shoppers may focus solely on coil count. Though coil count is an important aspect of a mattress support system, other factors assist in coil performance. Shoppers also want to consider coil design, number of turns, the gauge of wiring, and tempering of steel when comparing innerspring support systems.

Coil Fatigue

When an innerspring coil loses load-bearing capacity. Coil fatigue typically occurs in lower-quality mattresses lacking tempered steel coils. Most innerspring systems provide decent initial support; however, cheaper coils soften and offer poor body support after prolonged usage.

Coil failure typically occurs at the center of mattresses where much of the weight rests. Once coils wear out, mattresses sag and overall quality of rest decreases. Individuals may find it difficult to get comfortable and feel lower back pain in the morning.

Coil Gauge

The thickness of a coil in an innerspring mattress. Gauges commonly range from 12 to 15, with lower numbers indicating thicker coils. Coil gauge primarily affects comfort levels of mattresses. A higher gauge coil provides a softer, springier feel, whereas a low coil gauge offers firm pushback.

Gauge thickness also impacts mattress durability. Mattresses with thick coils tend to last longer. However, most individuals replace mattresses before coil systems give out. Additionally, gauge does not serve as an indicator of the quality of a mattress.