What is spring density in a mattress?

Simply the Best says spring density helps make mattress-size comparisons fairer. Spring count is the number of coils in a mattress or a specified spring unit.

Brentwood publishes coil counts for different mattress sizes.

• Twin: 572 coils.
• Twin XL: 681 coils.
• Full: 727 coils.
• Queen: 789 coils.
• King: 975 coils.
• Cal King: 958 coils.

Microcoils, nanocoils, and minicoils can provide a transition between the comfort section and support core.

Pocketed coils and movement

Pocketed coils can move more locally than interconnected coils.

• Test the finished mattress with a partner, because pocketed construction may reduce one path for movement, but only a finished-mattress test can show whether a partner’s movement is noticeable.
• Brentwood says its Quantum side rails provide edge support, while Caliber head-and-foot coils offer a more supportive edge than foam encasement.

Microcoils in advertised counts

Adding a microcoil count to a core count does not mean the mattress has that many full-size primary support springs.

• Small coils in comfort layers create more room for airflow, which can help reduce heat retention around the body.
• Tom’s Guide describes microcoils as 1 to 4 inches tall, compared with standard coils at 6 to 8 inches.
• Hickory Springs markets microcoil layers with counts as high as 5,000 for a queen mattress, and describes its 4,000-coil queen Micro 4.0 as a substitute for latex and foam surface layers.

A high coil count alone does not prove that a mattress is sturdier or more durable. If the seller cannot define the number, do not use it as a quality score.

• Haven Sleep notes that 3,000 coils can describe sophisticated engineering or several layers of smaller springs.
• Metal quality, tempering, coil height and gauge, shape, and turns also affect how firm and supportive coils feel.
• GoodBed warns that a higher count can be achieved using flimsy coils.
• Check the coil gauge, working turns, and tempering.

Higher spring density can give designers more points to tune how a mattress responds. Microcoils respond more immediately to pressure, and zoned coils can target support to body curves and heavier areas.

• Pocket coils move independently and can dampen movement transfer, but their pockets and surrounding materials can still transmit some movement.
• Connected Bonnell coils can transfer movement across the bed, making them unsuitable for bed-sharers, according to Tom’s Guide.
• Pocket coils allow closer contouring and minimal motion transfer and noise, according to Sleep Foundation’s comparison table.

To understand coil feel, check gauge and working turns.

• Mattress coils are usually 13 to 17 gauge.
• Sleep Foundation characterizes lower-gauge coils as firmer and more durable, while higher-gauge coils are more responsive and flexible.
• Brentwood lists 13.75-gauge coils in dark-blue zones and 16-gauge coils in perimeter and white zones.
• GoodBed says coils with more working turns can make a mattress softer and more durable.
• Diamond Mattress advises asking for the coil gauge, working turns, and tempering.

Some mattresses contain multiple coil layers, while others alternate foam and microcoils. Overall support may vary with coil type, gauge, total count, and the full mattress design.

• An innerspring mattress can cover its coil unit with memory foam, wool, or fiberfill to form a comfort layer.
• A hybrid typically pairs a pocket-coil core with foam, latex, memory foam, gel-infused material, and/or wool.
• Brentwood describes a performance layer that eliminates the need for extra foam.
• A combined spring total does not establish that a mattress is twice as supportive.

Brentwood publishes counts by size, and the Pocket Spring Store FAQ lists another set of counts by size. Ask for a written construction breakdown if a retailer cannot separate main support coils from added comfort coils.

• GoodBed describes pocket coils as having no direct connection from one coil to another.

If a seller cannot define the coil count, do not use it as a quality score.

• Pocketed cores tend to contain multiple smaller coils, while Bonnell or offset coils are larger and tend to come in lower counts.
• Metal quality, tempering, coil height and gauge, shape, and turns also affect firmness and support.
• A mattress with a higher count can use flimsy coils.

Can different mattress sizes share the same advertised count?

These examples show only that the listed Queen and King counts differ by size; they do not establish whether different sizes can share an advertised count. Simply the Best says spring density can help make size comparisons fairer.

Do foam edges affect a mattress's spring count?

The facts do not establish whether foam edges affect a mattress's spring count, so ask whether the perimeter uses foam or added coils. Some manufacturers reinforce the perimeter with additional low-gauge coils.

Does spring density mean the actual coil count?

Spring density divides the support-spring count by mattress area, so it is not the actual coil count. The illustrative queen example uses 800 main pocket springs and its 1.53 m × 2.03 m dimensions for the calculation.

We read 10 published pages from 10 sites (simplythebest.com.au, Sleep Foundation, help.brentwoodhome.com, sleepiverse.com and 6 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.