Mattress Coil Guide – What to Know About Coil Types

Understanding mattress coils is essential when choosing a new mattress. Coils impact support, comfort, durability, and motion isolation. Coil systems vary by shape, thickness (gauge), and construction, each offering unique benefits and drawbacks.

Key Coil Features

Shape: Hourglass, cylindrical, or continuous wire designs.
Gauge: Refers to coil thickness. Lower gauge = thicker, firmer coils; higher gauge = thinner, softer coils.
Working Turns: The number of turns in a coil impacts softness and longevity. More turns generally mean a softer feel and longer lifespan.

Bonnell Coils

Bonnell coils are a traditional innerspring system still found in many entry-level mattresses in 2026. These coils are shaped like an hourglass and connected by helical wires.

Pros: Cost-effective, provides firm support, widely available.
Cons: Prone to motion transfer, can develop pressure points, may sag over time as connecting wires loosen.

Offset Coils (Bonnell Variation)

Offset coils are an improved version of Bonnell coils. They use hourglass-shaped coils with squared sides, hinged together by helix wires. This design allows for better body conformity and reduces noise.

Flexes under light pressure and increases support with added weight.
Better contouring to body curves compared to standard Bonnell coils.
Less likely to sag and generally quieter.

Offset Coils

Offset coils are also hourglass-shaped but feature flattened edges, allowing each coil to compress and hinge more easily. This provides enhanced support and durability.

Offers more bounce and support than all-foam mattresses.
Less prone to sagging over time.
Often used as the core in mattresses with thick comfort layers.

When evaluating offset coil mattresses, consider:

Working turns: More turns mean longer-lasting, stronger coils.
Gauge: Thicker wire (lower gauge) feels firmer; thinner wire (higher gauge) feels softer.
Resiliency: Higher resistance coils retain shape better under pressure.

Continuous Coils

Continuous coils, also known as miracoils, use a single piece of wire to form rows of coils throughout the mattress. This system is common in budget and mid-range mattresses.

Pros: Durable, cost-effective, resists sagging.
Cons: Can be noisier than offset coils, less effective at reducing motion transfer.

Continuous coils are a good choice for durability but may not be ideal if you share your bed and want minimal motion transfer.

Other Coil Types

Pocketed (Marshall) Coils: Each coil is individually wrapped, allowing independent movement and superior motion isolation.
Microcoils / Nanocoils: Small, flexible coils often used in comfort layers or as a transition layer for added responsiveness and pressure relief.

Some hybrid mattresses combine microcoils with memory foam or latex for enhanced comfort and support.

Microcoils

Microcoils (also called nanocoils or minicoils) are tiny, flexible springs used in comfort or transition layers of modern mattresses. They provide a deep cradle for balanced pressure relief and spinal support.

Manufactured by winding fine wire into tight coils.
Improve responsiveness and durability.
Common in hybrid mattresses for a blend of bounce and contouring.

When considering a mattress with microcoils, look at both coil gauge (thickness) and coil count (density). Higher coil counts usually mean better durability, but comfort also depends on the quality of foam layers used with the coils.

Choosing the Right Coil System

Budget: Bonnell and continuous coils are most affordable.
Support & Longevity: Offset and pocketed coils offer better body contouring and durability.
Motion Isolation: Pocketed coils and microcoil hybrids are best for minimizing partner disturbance.

Always check coil gauge, coil count, and the number of working turns for a complete picture of mattress quality.

Frequently Asked Questions

What is the difference between Bonnell and offset coils?

Bonnell coils are hourglass-shaped and connected by helical wires, offering firm support but more motion transfer. Offset coils are a variation with squared edges and hinged connections, providing better body contouring, reduced noise, and improved durability.

Are continuous coils good for couples?

Continuous coils are durable and cost-effective but tend to transfer more motion than pocketed or offset coils. Couples sensitive to movement may prefer pocketed coil or hybrid mattresses.

What does coil gauge mean in a mattress?

Coil gauge refers to the thickness of the wire used in mattress coils. Lower gauge numbers mean thicker, firmer coils; higher gauge numbers mean thinner, softer coils. Most mattresses use gauges between 12 and 15.

Do more coils mean a better mattress?

Higher coil counts can improve support and durability, but coil quality, gauge, and construction are equally important. A well-made mattress with fewer high-quality coils can outperform one with many low-quality coils.

What are microcoils, and are they worth it?

Microcoils are small, flexible springs used in comfort or transition layers to add responsiveness and pressure relief. They are often found in hybrid mattresses and can enhance comfort and durability, especially when combined with quality foam layers.