Foam Mattress Guide: Types, Density & How to Choose

A foam mattress uses one or more layers of compressed foam as its primary support system — without springs or coils. Foam mattresses dominate Australia's online mattress market because they ship easily, deliver excellent pressure relief, and come in a range of feels from plush to firm. The trick is knowing which type of foam suits your sleep style.

Key Takeaways

• Foam mattresses come in four main types: memory foam, polyfoam, latex, and open-cell foam (Kloudcell®).
• Memory foam contours closely but can retain heat. Polyfoam is bouncier and more affordable. Latex is durable and naturally cool. Open-cell foam combines memory foam contouring with sprinfoam's biggest weakness gs-style breathability.
• Density (lbs/cubic ft) affects durability and cost more than comfort.
• Quality foam mattresses last 7–10+ years, with high-density foams lasting longer.

This guide breaks down the main foam types, explains density and firmness, and shows how to match a foam mattress to your sleep style.

Types of Foam Mattresses

Foam mattresses use one of four main foam types, each with different feel, durability, and price points.

Memory foam (viscoelastic). Soft, slow-responding foam that contours to your body when warmed by your body heat. Excellent pressure relief; can retain heat.

Polyfoam (polyurethane). A more responsive, bouncier foam used in budget mattresses and as a transition layer in more premium designs. More breathable than memory foam, less expensive.

Latex. Naturally derived from rubber trees (or synthetically produced), latex is springy, durable, and naturally cool. Premium price point but the longest-lasting foam type.

Open-cell foam (like Koala's Kloudcell®). A modern category designed to fix memory foam's biggest weakness — heat retention. Open-cell foams have an engineered structure that lets air flow through the mattress while still providing the contouring of memory foam. Tested to be up to 40% cooler to the touch and 30× more breathable than worst-performing competitor foams.

Pressure relief and support differences. Memory foam and open-cell foam (Kloudcell®) lead on pressure relief because they conform closely to the body. Latex is the most responsive — easiest to move on. Polyfoam sits in the middle on both metrics, which is why it often appears as a transition layer rather than the main support layer.

Memory Foam Mattresses

Memory foam (technically "viscoelastic foam") is the most well-known foam type. It contours closely to your body, distributing weight and reducing pressure on hips, shoulders, and lower back.

How memory foam responds. Memory foam softens when exposed to body heat, which is why you sink in slowly when you lie down. As you cool down or move, the foam returns to its original shape.

Temperature-sensitive properties. Because memory foam responds to heat, it can retain warmth — a common complaint, particularly in Australian climates. Newer designs include cooling technologies (gel infusion, copper, plant-based formulations) that help, though the trade-off persists.

Pressure point relief. This is where memory foam excels. The slow-conforming structure cradles the hips and shoulders, making it a frequent recommendation for side sleepers and those with joint discomfort.

Off-gassing timeline. New memory foam mattresses release a mild chemical smell from volatile organic compounds (VOCs) — typically dissipating within 24–72 hours. Most off-gassing odour clears within a few days to two weeks, so open the bedroom windows for the first day to speed up the process.

For more on memory foam toppers and how they differ from full mattresses, see our memory foam mattress topper guide. If you want memory foam's contouring without the heat retention, the Koala SE Mattress uses Kloudcell® open-cell foam — designed to solve exactly that problem. 

Polyfoam Mattresses

Polyfoam (polyurethane foam) is more responsive and bouncier than memory foam, making it a popular choice for budget and mid-range mattresses.

More responsive than memory foam. Polyfoam recovers quickly when you move — closer to the feel of latex than memory foam. This makes it easier to change positions and reduces the "stuck in it" feel that bothers some sleepers.

Budget-friendly. Most affordable mattresses use polyfoam in the comfort layers because it's cheaper to produce than memory foam or latex.

Support and bounce. Polyfoam delivers a firmer, more responsive feel that suits stomach sleepers and those who don't want to sink into the mattress.

Breathability. Polyfoam is more breathable than traditional memory foam — though still less so than open-cell foam, springs, or latex.

Durability and longevity. Standard polyfoam lasts 5–8 years, slightly less than memory foam. Higher-density polyfoam can last longer but is rare in budget mattresses.

Best for entry-level comfort. Polyfoam mattresses suit guest rooms, kids' beds, share houses, or as a budget option for solo adults who don't need premium contouring.

Latex Mattresses

Latex mattresses use rubber-derived foam — either natural (from rubber trees) or synthetic — for support. Latex is the most durable and naturally cool of the foam categories.

Natural latex. Derived from rubber tree sap and processed (Dunlop or Talalay methods). Natural latex is the most premium option, with excellent durability and natural breathability.

Synthetic latex. Lab-made from petroleum-based chemicals. Cheaper than natural latex but less durable and less breathable.

Blended latex. A mix of natural and synthetic, balancing cost and quality. The most common option in mid-range latex mattresses.

Bounce and responsiveness. Latex is the springiest of the foam types — almost like sleeping on a denser, cooler foam version of a coil mattress. Easy to change positions, no "sinking in" feeling.

Hypoallergenic. Natural latex is naturally resistant to dust mites, mould, and bacteria, making it a strong choice for allergy sufferers.

Durability and longevity. Latex is the longest-lasting foam, often holding shape for 10–15 years with proper care. The best long-term value if you can afford the upfront cost.

Premium pricing. Latex mattresses are the most expensive foam category, often costing 50–100% more than equivalent memory foam mattresses.

Foam Density Explained

Foam density measures how much foam material is packed into a given volume — typically expressed in pounds per cubic foot (lbs/cu ft) or kilograms per cubic metre (kg/m³). 

Low density (2–3 lbs/cu ft, ~32–48 kg/m³). Basic comfort foam. Cheaper, faster to break down. Common in budget mattresses and guest beds.

Medium density (3–5 lbs/cu ft, ~48–80 kg/m³). Standard quality foam used in most mid-range mattresses. Balances comfort, durability, and price.

High density (5+ lbs/cu ft, ~80+ kg/m³). Premium foam. Longer lifespan, deeper contouring, slower response. Used in premium mattresses and durability-focused designs.

Density vs comfort. A common mistake: assuming higher density means a firmer mattress. It doesn't. Density and firmness are independent — high-density foam can feel just as soft as low-density foam, but it'll last longer.

Density and lifespan correlation. Higher density foams resist sagging and indentations far better than low-density alternatives. If you want a mattress that lasts 10+ years, prioritise density over price.

Firmness Levels

Firmness describes how soft or hard a mattress feels when you lie down — completely separate from density. The same density foam can be made soft, medium, or firm depending on construction.

Soft foam. More cushioning, deeper sink, excellent pressure relief. Best for side sleepers, lighter-framed people, and those who like a plush feel.

Medium foam. Balanced support and comfort. The most popular firmness, suiting most adults and combination sleepers.

Firm foam. Less sink, more support, easier to change positions. Best for back and stomach sleepers, heavier-framed people, and those who prefer a flatter sleeping surface.

Matching to sleep position:

• Side sleepers: medium-soft to medium

• Back sleepers: medium to medium-firm

• Stomach sleepers: medium-firm to firm

• Combination sleepers: medium

For more on matching mattress firmness to your sleep style, see our best sleeping position guide.

Temperature & Cooling Technology

Heat retention is the most common complaint about foam mattresses — particularly traditional memory foam. Modern designs address this with several cooling technologies:

Memory foam heat retention. Traditional memory foam's dense, conforming structure traps body heat. In Australian summers or for hot sleepers, this can be uncomfortable.

Gel-infused foam. Memory foam with cooling gel particles or layers to absorb body heat. Research shows gel can lower mattress surface temperature by about 2–3°C in lab tests, though real-world cooling depends on the gel type and the overall mattress design. 

Plant-based foam. Some petroleum content is replaced with plant-derived oils. More breathable than traditional memory foam, naturally cooler, and often considered more eco-friendly.

Open-cell foam (Kloudcell®). Engineered with an open structure that lets air move through the foam. Koala's Kloudcell® is tested to be 40% cooler to the touch and 30× more breathable than worst-performing competitor foams. Specific Koala mattresses go further:

• Koala Plus: sleeps 13% cooler than leading online brands
• Koala Polar+: sleeps 5°C cooler than the Plus, with PolarBands™  technology
• Koala Luxe: uses copper-infused Kloudcell® and phase-change materials for active temperature regulation

Graphite and copper infusion. Like gel, graphite and copper conduct heat away from the body. Copper has the added benefit of being antimicrobial.

Best for hot sleepers. Open-cell foam (Kloudcell®), latex, or hybrid designs are the best foam picks for hot sleepers.

Support & Pressure Relief

Foam mattresses excel at pressure relief — the soft, contouring layers cradle the body and distribute weight evenly. This is the core reason memory foam, open-cell foam, and latex are popular for side sleepers and those with joint discomfort.

Contouring benefits. When foam contours to your body, it eliminates pressure points where bones meet the mattress (hips, shoulders, knees). Without those pressure points, you toss and turn less.

Pressure point relief. This is the standout strength of foam compared with traditional spring mattresses. Coils press back uniformly; foam responds to where you actually need support.

Support for different sleep positions. Different firmness levels suit different positions — see the section above. Foam works for all sleep positions; the right firmness depends on which one you favour.

Spinal alignment. A properly chosen foam mattress keeps the spine aligned with the rest of the body. Too soft and the hips sink, creating a dip; too firm and the natural curves can't relax.

Comfort vs durability trade-off. Softer foams feel more luxurious but break down faster. Firmer foams hold up longer but feel less cushioned. High-density foam (5+ lbs/cu ft) gives you both — softness with longer life — at a higher price point.

Durability & Lifespan

Quality foam mattresses typically last 7–10 years, with significant variation by foam type and density. 

Memory foam expected lifespan. 6–10 years for standard density; 10+ years for high-density premium memory foam.

Polyfoam lifespan. 5–8 years. Polyfoam is the most affordable but also the shortest-lived foam type.

Latex lifespan. 10–15 years. The longest-lasting foam category by a significant margin.

Open-cell foam (Kloudcell®) lifespan. Quality open-cell foams last 10+ years. Koala backs its mattress range with a 10-year warranty.

Density impact. Higher density correlates strongly with longer lifespan. A 5 lbs/cu ft foam mattress will outlast a 3 lbs/cu ft mattress by years.

Sagging and wear patterns. Foam mattresses typically develop body indentations in heavily used spots before they fail entirely. Once the indentation is more than 2–3 cm, replacement is overdue.

Quality grades and durability. Look for verified certifications (CertiPUR-US® in foam) and explicit warranty terms. Brands that are confident in durability offer 10+ year warranties. 

Off-Gassing & Smell

Off-gassing is the slight chemical smell new foam mattresses release as they expand. Most people don't find it bothersome, but it's worth knowing what to expect.

What is off-gassing? Foam contains volatile organic compounds (VOCs) used during manufacturing. When the mattress is unsealed, these gases dissipate into the air, releasing a faint smell.

Timeline. According to the Sleep Foundation, new memory foam typically has a noticeable smell for 3–7 days after unboxing, with most volatile organic compounds (VOCs) fully dissipating within 2–4 weeks. CertiPUR-US® certified foam tests well below WHO and EPA air quality limits, so the smell fades faster. Sensitive sleepers should air the mattress in a well-ventilated room for 1–2 days before sleeping on it. 

Ventilation importance. Open windows, run a fan, or move the mattress to a well-ventilated room. Airflow speeds up the process significantly.

Safety. VOCs from CertiPUR-US® certified foams are below regulatory thresholds  and considered safe for adults and children. The smell is more an aesthetic issue than a health one.

Minimising odour. Air the mattress before putting bedding on, or sleep on it the first night with the windows open.

When smell indicates an issue. If the smell persists past a week, or if it's strong enough to cause headaches, contact the manufacturer. Some mattresses ship with manufacturing defects that produce stronger-than-normal off-gassing.

Foam Mattress vs Other Types

How does foam compare to other mattress categories?

Foam vs coil mattresses. Foam wins on pressure relief and motion isolation; coils win on bounce and traditional cooling (though open-cell foams close that gap). For a deeper comparison, see our what is a coil mattress guide.

Foam vs latex. Latex is technically a foam, but it's responsive and naturally cool — closer to springs in feel than to memory foam.

Hybrid advantages. Hybrids combine foam comfort layers with pocket springs. The best of both worlds for many sleepers, but heavier and more expensive than pure foam.

For broader mattress recommendations, see our guide to the best mattress.

Ready to upgrade your sleep?

Koala's mattress range is built around proprietary Kloudcell® open-cell foam — tested to be 40% cooler to the touch and 30× more breathable than worst-performing competitor foams. Designed by Koala in Sydney, backed by a 120 day trial and 10-year warranty, with free mattress delivery Australia-wide. 

Shop Koala's mattress range →

Foam Mattress FAQs

What is the difference between memory foam and polyfoam? 

Memory foam (viscoelastic) responds to body heat and pressure, contouring to your shape for targeted support. Polyfoam is more responsive and bouncy, doesn't retain as much heat, and is typically more affordable.

Do foam mattresses sleep hot? 

Traditional memory foam can retain heat, but modern foam mattresses use cooling technologies like gel infusion, graphite layers, and ventilated designs to manage temperature. Open-cell foams (like Koala's Kloudcell®) close the gap further — tested to be 40% cooler to the touch than worst-performing competitor foams. If you sleep hot, look for these features.

How long does a foam mattress last? 

A quality foam mattress typically lasts 7–10 years, depending on density and usage. Higher-density foams (5+ lbs per cubic foot) tend to last longer and resist sagging better than lower-density options. Koala's Kloudcell® mattresses come with a 10-year warranty.

What does foam mattress density mean? 

Density measures how much a cubic foot of foam weighs. Low density (under 3 lbs) is softer and less durable, medium density (3–5 lbs) suits most sleepers, and high density (5+ lbs) offers the best long-term support. From Koala's premium range, the Koala Luxe Mattress features a 9 cm Kloudcell® comfort layer (50% more than the SE) and 7 multi-layered support zones — built for premium durability. 

Is the off-gassing smell from a new foam mattress harmful? 

The initial smell from a new foam mattress is caused by volatile organic compounds (VOCs) and typically dissipates within 24–72 hours. Unbox in a well-ventilated room and allow the mattress to air out before sleeping on it.