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Bed Basics: Compare mattress coils

mattress shopping
mattress shopping
Know how to compare mattresses before you head out shopping.

So you’re shopping for a new mattress, and you need an easy way to compare models. In our last post, we talked about the three basic elements of a mattress: coils, upholstery layers, and foundation. Today, we’ll look more closely at the types of coils, or springs, you’ll see in different mattress styles and what that means for you.

Coils are the steel springs inside the mattress. They’re typically arranged in some kind of pattern with each coil evenly spaced. There are several different kinds of coils, each offering its own benefits and drawbacks. When you’re shopping for a new mattress, be sure to compare mattress coils for a good understanding of how the mattress will respond to your weight at night and over its lifetime.

innerspring mattress coils
The Bonnell coil system.

Bonnell coil – Hour-glass shaped and attached to a frame by knotting the end of the coil over the frame; also laced together with another, usually more slender, spiral-shaped wire called a helical wire. This is the original innerspring bed coil, and the simplest. Usually a lower-cost option, but less flexible, doesn’t mitigate partner movement, and shorter lifespan.

Pocket coil – Barrel-shaped and individually wrapped in a fabric pocket. Each pocket is then attached together in a grid pattern. Thinner gauge wire allows for more initial flexibility, wider middle section of coil provides firmer support. Better motion separation.

Beautyrest black pocket coils
Simmons pocket coils - springs contained in fabric sleeves.

Offset coil – Similar to a Bonnell coil in that it’s hour-glass shaped, knotted to a frame, and connected with helical wires, but the top and bottom of the coils are squared off rather than circular. The squared heads should allow for the spring to contour more closely to the body shape. Typically more expensive.

Continuous coil – Rows of coils are made of one long, continuous piece of wire. Each row is attached to the next with helicals. There’s good weight distribution with continuous coils, so they may stay in their original condition longer. Also will typically result in a higher “coil count.”

Mattress makers will usually specify the gauge of the coil. The lower the number, the thicker the wire. While common sense would say thicker wire equals better quality or a longer lifespan, the style of the coil plays a significant role.

compressed coils
The springs compress when you lie down. Ideally, the coils compress enough to be comfortable but resist enough to keep your spine straight.

Similarly, you might think that more coils means a better mattress, but it’s equally important to consider how the coils are arranged and the gauge of wire. However, it is safe to say that in general, a mattress with a lot of heavy-gauge wires will be quite firm (at least at the beginning of its life), while fewer coils and thinner wires will have more give.

Simmons mattresses, like the Beautyrest TruEnergy, use a patented pocket coil system. It flexes comfortably when you lay on it but also offers good resilience and support so your mattress doesn’t sag where your weight settles the heaviest. The biggest benefit is motion separation; your partner can flop around without shaking you out of bed.

When you’re shopping for a mattress, make a list of what’s most important, and consider how coil styles can help you get the comfort and support you need.