Mattress thickness is one of the most overlooked parts of the buying decision. Most shoppers focus on firmness, material, and price, and then pick whatever height the mattress comes in without much thought. But thickness directly affects comfort, support, and how the mattress performs for your specific body over time. Getting it right matters more than most shoppers expect. These five tips will help you make the decision with confidence.
Before covering the five factors, BedsCrafters' complete mattress guide walks through the full buying process from type to firmness to sleep position. This article focuses specifically on thickness as a standalone decision point.
Tip 1: Match Thickness to Your Body Weight
Body weight is the single most important factor in determining appropriate mattress thickness. Heavier sleepers compress mattress layers more deeply than lighter sleepers. The support core needs to be substantial enough that you don't sink through the comfort layer and bottom out against the base.
For sleepers under 70kg, a mattress in the 18 to 25cm range is typically more than sufficient. The body doesn't compress deeply enough to need a thicker profile. For sleepers between 70kg and 100kg, a thickness of 25 to 30cm provides good support and comfort across most mattress types. For sleepers over 100kg, a mattress of at least 30cm is strongly recommended. This ensures there's enough material in both the comfort and support layers to perform as designed without compressing fully.
A mattress that's too thin for your weight will likely develop premature sagging and reduced pressure relief. The feel becomes increasingly unsupportive over time.
Tip 2: Consider Your Sleep Position
Your primary sleep position affects how much cushioning the comfort layer needs to provide. That directly affects how thick the mattress should be.
Side sleepers require deeper cushioning at the hips and shoulders to relieve pressure at those contact points. This cushioning has to come from somewhere, and it comes from a more substantial comfort layer. A thicker mattress makes it easier to include a comfort layer deep enough to do this properly without compromising the support core beneath it. Side sleepers generally do better on mattresses from 25cm upward.
Back and stomach sleepers don't sink as deeply into the comfort layer because their weight is distributed more evenly across the surface. They can do well with slightly thinner mattresses, especially if they prefer a firmer feel and don't need as deep a comfort layer. That said, most quality mid-range mattresses sit in the 25 to 30cm zone. This works well for all positions and is a sensible default when you're unsure where to start.
BedsCrafters' mattress collection lets you filter by sleep position and thickness. This makes it easy to see which options are recommended for your specific needs.
Tip 3: Factor In Your Foundation Type
Your bed base affects how thick your mattress should be in ways that aren't immediately obvious. Different foundation types add height and support in different ways, and this changes the effective feel and performance of the mattress on top.
Slatted bases allow the mattress to flex slightly between the slats. This can make a firmer mattress feel marginally softer than it would on a solid base. Solid or platform bases give a completely flat surface. This makes the mattress feel truer to its stated specification. Adjustable bases that bend and flex require a mattress designed to move with them. These are often on the thinner side to maintain the necessary flexibility.
If you're placing your mattress directly on the floor, thickness matters more because you lose the elevation and airflow that a base provides. A slightly thicker mattress on the floor gives you enough material depth to sleep comfortably. It also gets you further from the floor, which improves airflow and reduces moisture buildup underneath.
Tip 4: Think About Getting In and Out of Bed
The total height of your sleep surface matters for practical daily use. This is especially true for older sleepers, people with joint problems, or anyone who finds getting in and out of bed physically challenging.
The combined height of your mattress plus your bed base determines your final sleeping height. A practical target is a total height that lets your feet rest flat on the floor when sitting on the edge of the bed. This makes standing up easier and reduces strain on knees and hips during the transition.
If your base is already on the lower side, a thicker mattress brings the sleeping surface to a more comfortable height. If your base is very high, a thinner mattress may actually be more practical.
Tip 5: Understand the Comfort Layer vs. Support Core Relationship
Mattress thickness is not just one number. It breaks down into two distinct zones: the comfort layer at the top and the support core below it. Understanding this helps you evaluate whether a mattress is thick in the right place.
The comfort layer is what you feel when you first lie down. It provides pressure relief and surface cushioning. A quality comfort layer is typically 5 to 10cm thick in a well-specified mattress. Thicker comfort layers provide more pressure relief but can reduce support if the core beneath them isn't strong enough.
The support core is what keeps your spine aligned and prevents you from sinking too deeply. It makes up the bulk of the mattress's thickness. A quality support core is typically 15 to 20cm for most sleeping weights. For heavier sleepers, a denser and thicker core is important.
A 32cm mattress with a 15cm comfort layer and a 17cm support core performs very differently from one that's 32cm due to thick base foam with minimal cushioning. Same height, very different sleep. Total height says nothing about where that height is distributed. When comparing options, ask about how the thickness is distributed between the layers, not just the total height.
If you're ready to explore options by thickness and layer configuration, the full BedsCrafters shop range includes product specifications clearly listed for every mattress.
A Note on Mattress Thickness for Children
Children's mattresses are typically thinner than adult mattresses, usually in the 10 to 18cm range. This is appropriate for lighter body weights and lower beds. When a child moves to a standard adult bed, match the mattress thickness to their weight and the bed height. Going straight to an adult specification usually isn't necessary.
Frequently Asked Questions
Is a thicker mattress always better?
Not necessarily. More thickness is only better if it provides comfort or support you actually need. For lighter sleepers on a solid base, a mattress in the 20 to 25cm range can perform very well. Thickness should be matched to your body weight and sleep position, not chosen for its own sake.
What is the ideal mattress thickness for most adults?
For adults in the 70 to 100kg range, 25 to 30cm gives a good balance of comfort and support. This applies across most mattress types and sleeping positions. This range accommodates most sleeping positions and mattress types.
Does mattress thickness affect firmness?
Indirectly, yes. A thicker comfort layer will create a softer surface feel. A thinner comfort layer over a firm support core creates a firmer feel. Thickness and firmness are separate specifications but are related through how the layers are designed and proportioned.
Can I use a thin mattress on a thick base?
Yes. What matters is the combined height and whether the mattress provides adequate support for your body weight. A quality 20cm mattress on a solid platform base can outperform a poorly specified 30cm mattress on a sagging slatted base.
How does mattress thickness affect temperature?
Thicker mattresses with deeper foam layers tend to retain more heat. If you sleep hot, balance thickness with breathable materials like latex or pocket spring cores. Adding depth through dense foam layers will make the temperature problem worse.
Key Takeaways
Body weight is the primary driver of appropriate mattress thickness, and it should be your first consideration. Heavier sleepers need more material in both comfort and support layers. Side sleepers benefit from thicker mattresses that can accommodate a deeper comfort layer. Foundation type affects how a mattress performs and can influence the ideal total height. Getting in and out of bed comfortably depends on the combined height of your mattress and base. Thickness is only valuable if it's in the right layers. Understanding the comfort layer and support core split is more useful than the total height number alone.
The Bottom Line
Choosing mattress thickness isn't complicated once you understand the factors at play. Match thickness to body weight first. Then factor in your sleep position and foundation type and consider the practical height of your sleeping surface. A mattress that's the right thickness for your specific situation will consistently outperform a thicker or thinner one that doesn’t match your needs.