This replacement comfort foam layer is the firmest foam we offer for a Sleep Number® bed — the layer that sits on top of the air chambers and gives the surface its feel. It delivers an extremely firm, rigid surface with little to no give. Replacing a worn comfort layer eliminates body impressions and sagging, without touching the air chambers, pump, or cover you already own. Made in the USA and CertiPUR-US® tested.
Extra-firm feel
1.8 lb density
50 ILD firmness
1"–4" thickness
CertiPUR-US® tested
Made to order, USA
Have a King Split-Head FlexTop bed? FlexTop is a specialty size — a solid foam layer with a 34" cut at the head so each side raises independently. Shop the correct size in our
FlexTop Split-Head collection →
Trying to fix a sagging bed? Most people want our medium foam, not this one. If your goal is to firm up a bed that has gone soft, our
medium regular foam is the right call about nine times out of ten — and because you have a Sleep Number bed, you can dial the air chambers firmer on top of that. This firm foam is for the rare sleeper who truly wants an extremely hard, almost board-like surface.
What this foam feels like
This is by far the firmest option in our foam line — an extremely firm, rigid feel with little to no give, close to lying on a board. It does not cushion or contour; it is built purely for maximum, unyielding support. This is an outlier choice for sleepers who specifically want a rock-hard surface, not a general fix for a soft or sagging bed.
If you are here because your bed sags and you know you need something firmer, the medium regular foam is almost certainly the one you want. It restores firm, even support and matches the original Sleep Number feel, and you can then adjust your air chambers firmer for extra support. Customers who choose this firm foam to fix a sagging bed most often find it far too hard. Only choose this firm foam if you genuinely prefer an extremely hard mattress.
Which thickness should I choose?
The thickness you pick sets how much foam sits over the air chambers, and it also affects your shell height. Most beds use a 2" or 3" comfort layer.
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Match what you have to keep the same shell height — measure your current foam and order the same thickness.
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Go thicker (for example 2" up to 3") for a deeper firm layer, but remember it raises your shell height by the difference, so order a cover to match if you are replacing that too.
Not sure how thickness ties into shell height? Our guide to measuring your Sleep Number bed walks through it, or call us at 610-327-2322.
Specifications
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Feel: extremely firm — the firmest of our foam options, with little to no give
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Density: 1.8 lb
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Firmness: 50 ILD
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Thickness options: 1", 2", 3", or 4"
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Quality: CertiPUR-US® tested
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Made to order in the USA to fit your size and thickness
Compare our Sleep Number foams
All of our comfort foams are made to order in the sizes and heights shown on each product. Here is how the feels compare so you can pick the right one:
| Foam |
Feel |
Firmness |
Best for |
| Soft Regular |
Plush, sink-in |
12 ILD |
Softening a bed that feels too firm |
| Medium Regular |
Balanced, original feel |
35 ILD |
Most people; firming up a sagging bed (closest to original) |
|
Firm Regular (this page) |
Extra-firm, little give |
50 ILD |
Sleepers who want a very hard surface |
| Gel Memory |
Contouring, cooler, sink-in |
Medium (cradle) |
Pressure relief; plush premium feel |
| Latex |
Buoyant, responsive, on-top |
29 ILD (medium) |
Lively support; durable upgrade (not a Sleep Number foam) |
| Egg Crate |
Light cushion + airflow |
35 ILD |
Economical comfort and cooling boost |
Sizes & measurements
Choose your size below and the thickness (1"–4") that matches your bed. The foam lays over the air chambers inside the cover.
| Size |
Foam (W × L) |
| Twin |
38" × 75" |
| Twin XL |
38" × 80" |
| Full |
54" × 75" |
| Split Queen |
30" × 80" (per side) |
| Queen |
60" × 80" |
| Expanded Queen |
66" × 80" |
| King |
76" × 80" |
| California King |
72" × 84" |
| Split Cal King |
36" × 84" (per side) |
Will this fit my Sleep Number bed?
Because every layer is made to order, we fit older beds, newer smart-bed models, split and FlexTop setups, and sizes the manufacturer no longer sells — including Split Queen, Expanded Queen, and Split Cal King. If the foam sides of your bed have also softened, many owners refresh the perimeter at the same time with new foam side rails or the full complete rail set. Building a newer smart-bed model? You can build your own comfort layer instead. Browse everything on our Sleep Number foam & rails page or the full Sleep Number repair parts collection.
Frequently asked questions
What does this foam do?
It is the comfort layer that lays on top of the air chambers and gives the bed its surface feel. Replacing a worn comfort layer removes body impressions and sagging and restores a firm surface.
How firm is this foam?
It is by far the firmest option we offer — an extremely firm, rigid feel at 1.8 lb density and 50 ILD, with little to no give, close to lying on a board. It is noticeably firmer than our medium foam and firmer than Sleep Number original regular foam.
I just want to fix a sagging bed — should I get firm or medium?
For almost everyone fixing a soft or sagging bed, the medium regular foam is the right choice: it restores firm, even support, matches the original Sleep Number feel, and you can adjust your air chambers firmer for more support on top of it. This firm foam is an extremely hard, board-like surface meant only for sleepers who specifically want a rock-hard bed. Most people who buy it to fix sagging find it too firm.
What thickness should I order?
Match the thickness of your current comfort foam to keep the same shell height; most beds use 2" or 3". Going thicker adds a deeper firm layer but raises your shell height by the difference, which matters if you are also replacing the cover.
Is this foam safe and durable?
Yes. It is made in the USA, CertiPUR-US® tested, and built to hold up to daily use.
Will it fit an older or discontinued size?
Yes. Because it is made to order, we can match older, split, and discontinued sizes, including Split Queen, Expanded Queen, and Split Cal King.
What if the foam is too firm or too soft?
No problem — we offer a 30-day comfort exchange. Return it for a full refund or credit, or keep it and take a one-time 50% off a replacement (most people choose this — nothing to ship back). See our Foam Comfort Exchange & Return Policy for full details.
