How do mattress springs support your body?

Coils flex under pressure and provide firmer resistance as pressure increases. Comfort layers should ease pressure without letting the sleeper sink too far. How firm a mattress feels comes mostly from the comfort layers above the coils, so check those layers as well as the support core.

Coils Support, Layers Cushion

Coils respond to pressure and movement, while the comfort layers affect how plush or firm a mattress feels.

• Compare the listed comfort-layer materials and construction with the support-core details rather than judging the mattress from its coils alone.
• Check whether the comfort layers can conform enough to relieve pressure points without letting you sink too far.
• When a mattress description emphasizes its coils, also read what it says about the layers above them, since those layers shape much of the feel.
• Use both parts of the description to weigh feel and pressure relief: the coils respond to pressure, and the layers should conform without excess sink.

Microcoil height

Microcoils are shorter than standard coils, measuring 1 to 4 inches tall compared with 6 to 8 inches for standard coils.

• Check the listed coil height when a mattress description uses the word microcoil.
• Compare the stated height with both ranges, keeping microcoils and standard coils distinct.

Bonnell coils move as a single unit, while offset coils hinge under lighter pressure and push back more as the load increases. To compare these styles, look for the coil type in the mattress description and note how each responds to pressure.

Bonnell coils

Bonnell coils are interconnected, so they move as a single unit rather than adjusting separately.

• Look for “Bonnell” in the coil description to identify this connected construction.
• Keep in mind that Sleep Foundation says Bonnell coils cannot adjust to different weights.
• When comparing descriptions, note whether the coils are described as moving together, rather than assuming that all spring styles respond the same way.

Offset coils

Offset coils hinge under lighter pressure and provide stronger pushback as the load increases.

• Check whether the mattress description names offset coils if this change in response matters to your comparison.
• Compare the stated response under lighter pressure with the stronger pushback under an increased load.
• Read the description for the hinge response under lighter pressure and stronger pushback as load increases.

A supportive mattress perimeter can make it easier to sit on the edge and get in or out of bed. Bonnell coils generally have reliable edge support, but may sag in the mattress center.

Consider how you use the edge of the bed when comparing this feature. A stable perimeter can help you sit comfortably at the edge. The Bonnell coil detail comes with a separate caveat: those coils may sag in the center.

Keep the perimeter benefit and the center sag caveat distinct when reading a mattress description.

A queen innerspring or hybrid mattress may have 400 to 1,200 coils, but coil height, gauge, shape, turns, and steel treatment also affect firmness and support. Check the listed coil count alongside those construction details.

Use the product details to compare the coil count with the coil construction. The cited count range applies to queen innerspring and hybrid mattresses; the listed coil features also affect how firm and supportive the coils feel.

Coil gauge describes wire thickness, and the cited typical ranges differ. A lower gauge number means a thicker coil; Tom’s Guide also describes lower-numbered coils as firmer.

When comparing listings, read the gauge as a measure of spring thickness, not as a mattress-wide firmness score. The sources give different typical ranges, but both describe lower gauge numbers as thicker coils.

Firmness describes how hard or soft a mattress feels, and manufacturers may use different methods to describe it. A mattress that feels too firm or too soft can lead to strain or discomfort over time.

When comparing firmness labels, check how the manufacturer describes them rather than assuming every company uses the same method. The key question is how the mattress feels: firmness refers to its hard or soft feel, not a universal measurement shared by every manufacturer.

Treat an uncomfortable feel as a reason to look more closely at the mattress description, since makers may rate firmness in different ways.

Support can stay relatively uniform or target certain areas.

Uniform coils

Uniform support responds relatively evenly from head to foot.

• If your non-zoned mattress already feels comfortable and supportive, Yawnder says there is no reason to seek zoning.
• When checking a description, distinguish uniform support from a system that changes support by region.

Zoned coils

Some hybrid models have extra-gauge coils along the perimeter for stronger edges and across the center for targeted lumbar support.

• Check whether the description identifies extra-gauge coils at the perimeter or center.
• Note which area the coils are placed in: the perimeter is linked with stronger edges, while the center is linked with targeted lumbar support.
• Do not assume every hybrid has these additions; the fact applies to some hybrid models.

Side sleepers often benefit from plusher surfaces, while back sleepers generally need a mattress that resists sagging in the midsection.

Side sleepers

Side sleepers often benefit from a plusher surface that cushions or cradles the body.

• If you want cushioning or cradling, look for a plusher surface.
• Check the feel of an innerspring mattress carefully, since it can be too firm for side sleepers or lighter bodies.

Back sleepers

Back sleepers generally need a slightly firmer mattress that resists sagging in the midsection.

• Check whether the mattress description addresses midsection sagging.
• Innerspring mattresses are listed as an option for back sleepers.

Stomach sleepers

Tom’s Guide lists innerspring mattresses as ideal for stomach sleepers.

• Keep innerspring models in the comparison set if you are shopping for a stomach-sleeping option.
• Check the manufacturer’s firmness description as well, since manufacturers may use different methods to describe firmness.

Mattress builds differ in their coil structure and the comfort materials above the coils.

Innerspring

A traditional innerspring has a coil system with light padding, which gives it a bouncy, responsive feel.

• Check how much padding is described above the coils; thin padding does less for pressure points.
• Consider motion transfer when comparing this build, since the source says it tends to be higher.
• Look for a description of both the coil system and the padding to understand the stated feel and pressure-point tradeoff.

Hybrid

A hybrid combines an innerspring support core with a substantial comfort system.

• Check the product description for both the innerspring support core and the substantial comfort system.
• Tom’s Guide describes pocket-coil designs with comfort and transition layers around a pocketed-spring support core.
• In those designs, the listed comfort layers may include memory foam, wool, or latex.

Memory foam

Memory foam can provide pressure relief and motion isolation.

• Consider whether pressure relief is a priority when comparing memory foam.
• Consider motion isolation separately, since the source describes it as another feature memory foam can provide.

A sagging mattress may involve failure in the support core, springs, or bed base. You can check whether the surface has dropped with a straight edge or taut line, without pushing the tool into the foam.

1. Lay a straight edge or taut line across the mattress to see whether the surface has dropped.
2. Keep the measuring tool from pressing into the foam while checking the surface.
3. If the mattress uses Bonnell coils, note that Tom’s Guide says these budget coils can be noisy and prone to premature sagging.
4. If a low-priced spring mattress is on your list, check its coil type, since Bonnell coils are widely used in budget innerspring mattresses.

Are modern innerspring mattresses one-sided?

Not always: many modern innerspring mattresses are designed for one-sided use, so flipping may not be necessary or even possible. Some traditional innerspring mattresses have identical filling, springs, and padding on both sides. Check the maker’s care instructions for the specific mattress.

What does uniform coil support mean?

Uniform coil support means the system responds relatively evenly from head to foot, but the same mattress may feel softer to a heavier person and firmer to a lighter person. Interconnected Bonnell coils move as a single unit. If a non-zoned mattress already keeps you comfortable and well supported, Yawnder says there is no reason to seek zoning.

We read 13 published pages from 7 sites (Sleep Foundation, tomsguide.com, beautyrest.com, avocadogreenmattress.com and 3 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.