When the time comes to buy a new mattress, you'll need to figure out if you want a foam or spring model. There are all sorts of marketing claims from both camps regarding which type is better for certain sleepers, body types, support and more. But our tests have found that many of these so-called benefits are nothing more than myths.
A lot of it comes down to finding a mattress that feels right for you, though understanding the differences between the two will help you make an informed decision. Knowing the ins and outs of mattresses is much more useful than any marketing claims.
In a foam mattress the core is usually made from polyurethane or latex, with additional layers of varying densities on top and underneath.
A few of the mattresses that have come through our labs use multiple materials – e.g. a latex core with a polyurethane top, while others are nothing more than a single chunk of foam wrapped in protective fabric. Our tests have also found that latex models are generally heavier.
Latex mattress manufacturers claim that their products are 100% organic and are therefore a healthier alternative to polyurethane. However, this only applies if the latex is made from 100% sap as there are synthetic alternatives that use extra chemicals and fillers.
Foam vs memory foam
This all comes down to density. Almost all of the models that we've tested have a standard polyurethane or high resilience (HR) polyurethane top which has increased responsiveness. This is a fancy way of saying that the mattress has more of an even feel, consistent bounce and reduced sinking feeling when you lie down.
Memory foam, however, is a lower response version of polyurethane that can contour around your body. The mattress gradually returns to form when you get out of bed. HR polyurethane may provide some contouring but not as much as memory foam.
Even if a mattress is marketed as being memory foam, the memory foam is generally just one layer near the top and still has other layers of standard or HR polyurethane foam as well. The standard layers have firmer characteristics and usually provide support and shock absorption towards the top and bottom of the mattress.
Despite the name, these mattresses aren't solely made from springs because that's not exactly conducive to a good night's sleep. In this case, the core is a series of springs encased in foam layers on the top and bottom for added support and comfort. These layers are typically made of standard or HR polyurethane.
There are five spring types found in the vast majority of mattresses. Our body support tests found that there's no one type that consistently scores better than the others, but there are still some differences worth noting.
Bonnell – the classic hourglass spring design with a closed/wired off end. All the coils are interconnected and designed to work as a single unit to provide a broad, continuous level of support. Our tests show they can feel a bit bouncier or less stable, which can be transferred to another person sharing the bed.
Light spring – a similar design to Bonnell, however the end of each spring is left open.
Offset (also left-facing knot) – another hourglass coil spring design, but with a flat top and bottom that's held together with coiled wires. This claims to improve support and stability and reduce sagging thanks to better contouring around your body.
Continuous – all the springs are made from a single piece of wire to improve stability and extend durability, but at the expense of comfort.
Pocket – the most common spring type to come through our labs. Each one is wrapped in material (pocketed), often contains smaller coils and is designed to operate independently for improved support and contouring. Our tests show that pocket spring mattresses tend to have good stability and less change in comfort over the years.
Does spring count make a difference?
In all our years of testing we're yet to find any link between higher spring counts and improved performance.
Most spring and many foam mattresses include polyester and/or polypropylene layers in ticking and webbing. Some models also add additional layers throughout, not just at the top and bottom.
Note: We don't perform a smell assessment and can't comment on whether foam mattresses omit a chemical odour after opening. This process, commonly called 'off-gassing' supposedly lasts a few days.
This loosely defined category combines elements of spring and foam construction in the core. This is different to a typical mattress where the foam or spring core provides most of the support and foam layers are added for comfort.
Because there's no real hybrid mattress standard, you'll find a wide variety of models that claim to be hybrids. We apply the term when the foam and spring components provide equal levels of support, rather than just a comfort topper.
Manufacturers often claim that certain sleepers and body types are better suited to spring or foam mattresses. But there aren't any consistent results in our tests that indicate whether one type is more suitable than the other.
The best option is mostly a matter of personal preference towards the general 'feel'. Though there may be theoretical rules about how foam and springs differ, the build quality plays a significant role that ultimately determines how the mattress feels to you.
Our tests assess comfort and support in dorsal (back) and lateral (side) position. Until recently, this was conducted with people chosen to comply with the 5th percentile female (1.55m/54kg) and the 95th percentile male (1.91m/104kg).
We have since switched to dummies that comply to female (1.55m/55kg) and male (1.9m/100kg) heights and weights. This range covers 90% of the general population and are similar enough to allow our current results to be comparable with previous tests.
We haven't tested models that are advertised as being predominately memory foam and cannot comment on how those results compare to standard and HR polyurethane mattresses.
Lateral comfort and support measurements are key parts of our test.
Comfort, support and comfort retention
An equal percentage of foam and spring mattresses showed good, average and poor performance in these tests. To put it simply, there's a lot more that goes into support and comfort beyond 'foam versus spring'.
The best example of this are results for two Koala mattresses in our initial comfort tests – the Koala Mattress (2021 model) and the Calm As Mattress. The Calm As scored an average of 69% in the dorsal test and 56% in the lateral, while the standard Mattress scored 58% and 48% respectively.
They should be in the same ballpark due to the standard polyurethane foam cores used, if marketing is to be believed – but that's not the case. It's likely the different layering of various thicknesses of foams makes more of a difference.
Spring mattresses are also inconsistent. For example, the A.H. Beard King Koil Comfort Plus scored 59% and 49% while the Slumberland Sutton Pillowtop scored 72% and 57% in back and side sleeping positions respectively.
Foam mattresses are often marketed as the more stable, less bouncy option but our stability test says otherwise. About half of both the currently available spring and foam models in our test earned a score of 60% or higher. The highest rating models for stability were all pocket spring mattresses. However, Bonnell and light spring mattresses rated poorly.
This is one of the only areas with notable differences between foam and spring mattresses. Our tests measure the insulation to determine mattress warmth and the amount of sweat that's retained during a night's sleep.
A foam mattress is kind of a big sponge, if you think about it, so it makes sense that airflow isn't as good compared to a spring model. We found that more spring mattresses had a cool or very cool feel compared to the polyurethane foam models.
However, the two latex mattresses in our test were also cooler feeling, but still collected a lot of sweat. The spring models did a better job of repelling sweat, including two models that earned perfect results.
The currently available foam mattresses in our test range from $365 up to $1799 for a queen size. Spring mattresses can be as low as $200 and go over $5000. However, not only are mattresses frequently on sale, there's a lot of wiggle room in the RRP so you can get a much better deal with a little haggling. This is only really an option in bricks-and-mortar stores though where you can talk to the saleperson.
For example, the Sealy Posturepedic Exquisite Iridium, which has an RRP of $5199, cost us $2999 at the time of testing. We were also able to negotiate an additional discount on top of the sale price.
Our usage, wear and damage tests simulate eight years of use, which is the standard life expectancy for a good quality mattress. Comfort retention results – aka how similar the mattress feels after eight years compared to day one – were consistent across the different types.
There's an even spread of good, average and poor performers in all types in our test. However, there are fewer foam mattresses with notable sagging.
Foam mattresses may not last as long if you're prone to sweating due to a warmer climate or health reasons. Sweat absorption can damage the mattress over time and cause odours, so you may want to consider a spring model in this instance.
Unless you need a particularly cool bed or are worried about how much you sweat at night, there aren't any clear-cut reasons as to why you should pick a spring over a foam mattress (and vice versa). The main aspects – support and comfort – are equally good and bad, which shows that there's a lot more to consider than the core construction alone.
That's why it's best to use our test results as a guide and, more importantly, try before you buy. Most mattress-in-a-box brands have a 30–100 night at-home trial period and retailers typically have their full range on display in bricks-and-mortar stores.
Our test results can give you general information as to how a certain brand, or similar models, perform so you have an idea of what you'll get out of the mattress's lifetime. But feel is equally important, so take your time to try all the products you're considering to find the mattress that's right for you.
Stock images: Getty, unless otherwise stated.