The main mattress coil types are Bonnell, offset, continuous-wire, and pocketed coils. Connected coils tend to have more bounce. Pocketed coils can fit more closely to your body and pass less movement across the bed. Compare the whole mattress, not just its coil type or count, because its overall design also affects support.
The main types are Bonnell, offset, continuous-wire, and pocketed coils. Mattress coils are metal springs that flex under pressure and provide firmer support as pressure increases.
Bonnell, offset, and continuous-wire coils connect to their neighbors. Each pocketed coil sits in a fabric sleeve. Pocketed coils have no direct metal links to each other. Connected systems tend to have more bounce and make moving easier. But their links can carry movement across the bed.
Coil type
Construction
What to know
Bonnell
The coils are interconnected.
Often fairly firm and inexpensive. They may make noise or sag in the center. They may also adjust less well to different weights and sleep positions.
Offset
Coils resemble Bonnell coils, but squared sides flex like a hinge.
They can contour more and be quieter than Bonnell coils, but cost more to make.
Continuous-wire
One wire forms rows of coils joined by connecting wires.
Firm and stable, but they contour less than offset coils and can pass movement and noise.
Pocketed
Each coil is wrapped in fabric and can compress independently.
Closer contouring and less motion transfer may appeal to bed partners. Mattresses with individually wrapped coils may cost more than other coil mattresses.
Are microcoils, minicoils, and nanocoils different?
Microcoils and minicoils are interchangeable names for small springs, while nanocoils are shorter. These terms and sizes can vary across sources.
Microcoils and minicoils measure 1 to 4 inches tall.
Nanocoils typically measure no more than 0.75 inches tall.
For context, most innerspring coils are 6 inches or taller.
Small coils are most often used in comfort or transition layers rather than as the larger coils in the main support core. Microcoil and nanocoil layers can add contouring, bounce, and breathability; fabric or foam around them helps reduce motion transfer. They usually make a mattress taller, and the layers may creak with age. Microcoils are often covered by thin foam or quilting so you do not feel the individual coils.
Ask which layer contains them before using a small-coil count to compare support cores. Learn more about microcoil mattresses.
Do nested, dual-gauge, and coil-within-a-coil designs differ?
Yes. These terms describe different design choices, and their meanings can vary by maker.
Nested can describe how coils are arranged. Diamond describes its nested pocket coils as a honeycomb layout, with each coil in a gap between surrounding coils. Diamond says its layout creates a denser, more responsive surface.
Dual-gauge describes a design using different wire thicknesses. For example, Layla says its Hybrid uses 14-gauge pocket coils throughout and a double row of 16-gauge coils around the edge.
Coil within a coil places one spring inside another. Leggett & Platt says its fabric-encased DuoCoil has an outer coil with a soft, contouring feel and an inner coil that responds as weight is applied.
The term “dual coil” is sometimes used for a coil within a coil, rather than one coil layer on top of another. Ask the maker what its name means and where each coil is used.
Which coil type suits your sleep and preferred feel?
Try pocket coils for a closer fit to your body and less partner movement. Try connected coils if you prefer more bounce and easier movement. Neither choice settles how the whole mattress will feel.
Sharing a bed: Pocket coils can respond without passing as much movement to nearby coils. Partners are less likely to wake each other on a pocket-coil mattress.
Moving easily: Connected coils tend to have more bounce than pocket coils. They also make it easier to change position, but their links can carry motion across the bed.
Side sleeping: Some curvier side sleepers may find connected coils less appealing because they conform less closely. Pocket coils allow more precise contouring.
Seeking a firm feel: Bonnell and continuous-wire coils tend to be firm. Gauge and the rest of the mattress design matter too. Thicker springs may suit heavier sleepers because they provide stronger support, but they are not a guaranteed fit for everyone.
Offset coils can contour and limit motion better than Bonnell coils.
Edge design and mattress layers both matter. Some mattresses reinforce the perimeter with coils or foam, while zoning changes support in selected areas.
Innerspring and hybrid coil cores tend to have sturdier edges than other mattress types. This is especially true when they have added edge support. Some makers add lower-gauge coils at the edge. Designs differ, though. Brooklyn Bedding says its Ascension system uses higher-gauge edge coils for support.
A zoned mattress is usually firmer in its center third, which may also make the center of the edge feel more stable. A thick, soft comfort layer can make an edge feel less stable because you may sink farther before reaching the core. A firm mattress without dedicated edge reinforcement can still have a more supportive edge than a softer mattress with it.
Check several spots along the edge and ask where reinforcement is placed, since edge support can vary around the perimeter. See more on pocket spring edge support.
Coil-based mattresses tend to sleep cooler than all-foam mattresses because the coils leave room for airflow, but that does not rank coil types by temperature. Coil designs can differ in noise too. Continuous-wire coils are generally not as quiet as offset coils. Bonnell coils may make noise from friction.
One experiment measured four mattress constructions with different filling materials while one woman slept over six nights. The pocket-spring mattress had the highest recorded temperatures. The fillings also differed, so the result does not show that pocket coils are generally warmer or cooler than other coil types.
Consider the whole construction rather than assuming a coil name tells you how cool a mattress will sleep.
Gauge measures wire thickness: a lower gauge number means thicker wire. All else equal, thicker, lower-gauge wire makes a firmer coil, but it does not guarantee a firmer whole mattress.
For example, 13-gauge wire is thicker than 17-gauge wire. Higher-gauge coils are more flexible, while lower-gauge coils are generally firmer. Coil height, shape, metal quality, tempering, and the number of turns also affect how firm and supportive coils feel.
A maker may use different gauges in different areas for zoning or edge reinforcement. Ask for the gauge by layer or area, then judge it alongside the rest of the design. Read more about coil gauge.
More coils do not necessarily mean better comfort or support. Count is most useful when you compare similar sizes, coil types, layers, and construction.
A queen-size innerspring or hybrid mattress can have 400 to 1,200 coils, but that range is not a single ideal count. Pocketed support cores tend to have more, smaller coils than Bonnell or offset cores. Continuous-wire counts can also be hard to compare with counts from non-continuous systems.
A total may include small comfort-layer coils as well as support coils. Ask for separate counts by layer, and compare the same mattress size, coil dimensions, function, gauge, construction, and counting method. Size-based minimum rules of thumb differ, so do not treat one cutoff as a guarantee of quality. See does coil count matter?
Compare like with like, then consider how the complete mattresses feel. A coil label alone cannot tell you how supportive a mattress will be.
Match the mattress size. Ask for the coil type, dimensions, count, and counting method for each mattress.
Separate the layers. Ask which coils form the main support unit and which are microcoils or another coil unit.
Check the construction. Ask about gauge, coil height, shape, turns, metal quality, and whether the steel is tempered. Ask where any zoning and edge reinforcement sit.
Consider the comfort layers. A thicker, softer layer can change how the edge feels even when a mattress has a coil core. Compare the feel of the whole mattress rather than choosing on coil count alone.
We read 17 published pages from 14 sites (Sleep Foundation, goodbed.com, Saatva, mattressunderground.com and 10 more), checked in October 2026. Every sentence in the answers above cites one of them; the offer card at the end names its own source. This page reports published sources only; we did not test mattresses in person.