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Mattress Coil Types: An In-Depth Guide

By: Christina Davies
Updated on: April 05, 2024

When it comes to selecting a mattress, there are many factors to consider. One crucial aspect is the type of mattress coils used in its construction. Mattress coils are crucial in providing support, durability, and comfort. This comprehensive article will explore the different mattress coil types, their advantages and disadvantages, and how they contribute to your overall sleeping experience. If you want to buy a mattress that suits your sleeping style or needs, it’s important to know about the different types of coils inside the mattress. Whether you sleep on your side or back or have special requirements, this knowledge will help you make a smart choice.

What Are Mattress Coils?

Mattress coils are metal springs that provide support and a sturdy surface for sleeping. They can flex under pressure and become firmer as more weight is applied. These coils are typically made from tempered steel, which is repeatedly heated and cooled to make them resilient and maintain their shape with extended use.

Coil-based mattresses are known for their responsiveness and durability. They also stay cooler than all-foam mattresses because they allow airflow. The level of support in these mattresses can vary based on factors like the type of coils, their thickness (gauge), the total number of coils, and the overall mattress design.

There are four main types of coils used in mattress support cores: Bonnell coils, offset coils, continuous wire coils, and pocketed coils. Some mattresses incorporate micro-coils, nano-coils, or mini-coils in the comfort or transitional layers. Even within these main coil types, there can be slight design variations.

Mattress Coil Types

There are several types of mattress coils:

Typical Coil Count400 to 600500 to 2,000500 to 2,000800 to 1,200
Typical Cost$ to $$$$ to $$$$$$$
Typical GaugeLow to HighMedium to HighMedium to HighHigh
Joining AgentMetal Helicals and Wire ExtensionsMetal HelicalsMetal HelicalsGlue or Other Bonding Materials
ShapeHourglassHourglass with squared sidesSingle wire formed into loose coilsCylindrical springs encased in fabric

Bonnell Coils

Bonnell coils, initially the classic choice for mattress construction, feature an hourglass shape, wider at the top and bottom than in the middle. This design allows the thinner section to respond to light pressure while the thicker part handles heavier loads. These coils are interconnected through thin, spiral-shaped helical wires, forming a unified unit.

While the interconnected nature of Bonnell coils offers robust support, it comes with limitations. They struggle to adapt to varying weights and sleeping positions compared to other coil types. Additionally, friction between the coils may generate some noise. Originally, Bonnell coils were the first coils used in mattresses, and they’re among the most affordable. They’re firm and usually provide strong edge support, but they might sag in the middle over time.

Offset Coils

Offset coils are a type of mattress spring system that’s evolved from the Bonnell coils. They share a similar hourglass shape and interconnected helical wires, but some important distinctions make them more comfortable, responsive, and less noisy.

Unlike Bonnell coils with rounded tops and bottoms, offset coils have squared sides. This design allows them to act like hinges under light pressure, providing stronger support under heavier weight. These coils can adapt to your movements without transferring too much motion to the rest of the mattress, and their ergonomic shape also helps reduce noise.

Offset coils come in various variations. Some have hinges on both sides, some on the top and bottom, and there are even offset coils without knots. However, it’s worth noting that manufacturing offset coils is more expensive than Bonnell coils, which can increase the overall cost of the mattress.

Continuous Wire Coils

Continuous coils are made using a single wire formed into rows of loose coils linked together by helical wires. This uncomplicated design is both durable and budget-friendly. The helical wires evenly space out the coils within the frame, reducing the motion transfer. However, because they are tightly connected, continuous wire coils can still transmit some movement when pressure is applied. This is why they are not as quiet as offset coils.

Continuous wire coils provide a firm and stable support but do not conform to the body as much as offset coils. They are best suited for mattresses with thick comfort layers. Continuous coils are cost-effective to manufacture, requiring less time and money than other coil types, making them a more affordable option.

Pocketed Coils

Pocketed coils, also known as Marshall coils, are common in hybrid mattresses. These coils comprise many smaller coils, each wrapped individually in fabric. These fabric-wrapped coils are then sewn or glued together, allowing each coil to move independently within its fabric casing.

One significant advantage of pocketed coils is their ability to contour to the body’s shape effectively. Since each coil responds only to direct pressure, it can adapt to your body without disturbing the rest of the mattress. If you share a bed, you’re less likely to wake up your partner when you move on a pocketed coil mattress.

Pocketed coils have a cylindrical shape that helps evenly distribute pressure across each coil. This design is more durable, particularly in the center than other coil types with hourglass shapes, which can wear down more easily. The complexity of making pocketed coils can make them more expensive than other types of coils, but they also tend to be more durable and provide better support.

Microcoils, Nanocoils, and Minicoils

Microcoils, nanocoils, and minicoils are commonly used in mattresses’ comfort or transitional layers. These coils, made from flexible metal wires, enhance the mattress’s responsiveness, durability, and support.

Unlike standard innerspring coils, which are typically around 6 inches tall, micro-coils and mini-coils are shorter, ranging from 1 to 3 inches in height. Nanocoils are even smaller, with some measuring less than 1 inch in height. Most of these coils are individually wrapped to improve contouring.

The role of micro coils, nano coils, and mini coils is to transition from the comfort section to the support core. Their smaller size allows them to respond more quickly to pressure, creating a deep cradle that provides balanced pressure relief and support.

Incorporating these smaller coils also promotes better airflow in the mattress’s comfort layers, reducing heat retention around the body. You’ll typically encounter micro-coils, nanocoils, and mini-coils in hybrid mattresses. Some mattresses feature multiple layers of coils, while others use alternating layers of foam and micro-coils.

Advantages and Disadvantages of Different Coil Types

Each type of mattress coil has its own advantages and disadvantages. Understanding these features can help you select the correct coil type.

Bonnell Coils: Advantages and Disadvantages

The advantages of Bonnell coils include their affordability and durability. They provide a firm and supportive feel, making them suitable for individuals who prefer a firmer sleeping surface. Bonnell coils also offer reliable edge support, allowing you to utilize the full surface of the mattress.

However, Bonnell coils have some drawbacks. They may produce noise and motion transfer, making them less suitable for light sleepers or couples. Bonnell coils also have limited contouring ability, which may not provide adequate pressure relief for some sleepers.

Offset Coils: Advantages and Disadvantages

Offset coils offer several advantages over Bonnell coils. They provide better contouring and reduced motion transfer, resulting in a more comfortable and undisturbed sleep. Offset coils are also more durable and responsive, adapting to your body’s movements throughout the night.

The main disadvantage of offset coils is their higher cost than Bonnell coils. They are also more prone to sagging over time, which may affect the overall lifespan of the mattress.

Continuous Wire Coils: Advantages and Disadvantages

Continuous wire coils are known for their durability and affordability. They provide a stable and supportive sleep surface, especially with thick comfort layers. Continuous wire coils also have better motion isolation compared to Bonnell coils.

However, continuous wire coils may have limited contouring ability and can transmit motion when responding to pressure. They may also produce noise, especially if the coils are tightly connected.

Pocketed Coils: Advantages and Disadvantages

Pocketed coils offer superior contouring, motion isolation, and support compared to other coil types. The fabric pockets allow each coil to move independently, providing targeted support and pressure relief. Pocketed coils also have excellent motion isolation, making them ideal for couples or light sleepers.

The main disadvantage of pocketed coils is their higher cost than other coil types. However, the benefits of better support and motion isolation often outweigh the additional expense.

Coil Count and Coil Gauge

The performance of innerspring mattress coils depends on two main factors: coil gauge and coil count. The coil gauge refers to the thickness of the wire, while the coil count indicates how many springs are in the mattress. Coil gauge typically ranges from 13-gauge to 17-gauge. A lower gauge means a thicker coil, which results in a firmer and more durable mattress. Conversely, higher gauge coils are thinner and offer more flexibility and responsiveness.

When it comes to coil count in a queen-size innerspring or hybrid mattress, it can vary from 400 to 1,200. Pocketed coils are smaller and more numerous, while Bonnell or offset coils are larger and have a lower count. Some mattress manufacturers reinforce the mattress’s edges with extra low-gauge coils to provide better edge support.

A general guideline is to steer clear of mattresses with coil counts below 400 for a queen size. However, it’s essential to remember that a high coil count alone doesn’t guarantee a sturdier or more durable mattress. Other factors like the quality of the metal, whether it’s tempered, the coil’s height, gauge, shape, and number of turns all influence how firm and supportive the coils feel.

What Purpose Do Mattress Coils Serve?

Mattress coils serve a fundamental purpose: they support your body and ensure even weight distribution. These steel coils are crucial in stabilizing the bed and maintaining proper spinal alignment when integrated into innerspring and hybrid mattresses.

These coils can compress and expand in response to pressure, which helps buoy sleepers and gives the mattress a noticeable bounce. This makes coil-based mattresses generally easier to move on compared to all-foam models.

Typically, mattress coils are situated in the support core of the mattress. They offer deep spinal support from this position, while the comfort layers on top add cushioning and reduce the formation of pressure points. There are some exceptions to this placement, such as micro coils, mini coils, and nano coils, which are often used in the comfort layers. These smaller and more flexible coils serve a dual purpose: pressure relief and spinal support.

Coil-based mattresses are preferred for individuals who appreciate bounce and enhanced airflow. Mattresses with coil-based foundations support significant amounts of pressure, making them a great option for sleepers who weigh more than 230 pounds.


Are pocketed coils better than innerspring coils?

It depends on your preference. Pocketed coils offer better motion isolation, while innerspring coils provide excellent support.

Do hybrid mattresses last as long as traditional innerspring mattresses?

Yes, hybrid mattresses are designed for durability and can last as long as traditional innerspring mattresses.

Can I use a hybrid mattress on an adjustable bed frame?

Many hybrid mattresses are compatible with adjustable bed frames for added convenience.

Are coil mattresses suitable for side sleepers?

Yes, but consider pocketed coils for better contouring and pressure relief.

How can I prolong the lifespan of my mattress?

Rotate your mattress regularly, use a mattress protector, and follow the manufacturer’s care instructions.


Choosing the right mattress coil type is essential for a comfortable and restful sleep. Understanding the advantages and disadvantages of different coil types can help you decide based on your sleep needs and preferences. Whether you prefer the affordability of Bonnell coils, the contouring of pocketed coils, or the responsiveness of offset or continuous wire coils, a mattress coil type is perfect for you. By considering your sleeping position, body type, and personal preferences, you can select a mattress that provides the necessary support, durability, and comfort for a good night’s sleep.

Always consult with mattress experts or conduct thorough research before deciding. By choosing the right mattress coil type, you are investing in your sleep health and overall well-being. Happy mattress shopping!


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