How to Choose the Right Mattress Topper Thickness

Choosing the right mattress topper thickness is one of the most important decisions you'll make when shopping for bedding accessories. The depth of your topper directly impacts comfort, support, and how effectively it addresses your specific sleep needs. Too thin, and you won't notice much difference; too thick, and you might find yourself sinking uncomfortably or struggling to get in and out of bed.

In Australia, mattress toppers typically range from 2.5cm to 12cm in thickness, with the most popular options falling between 5cm and 8cm. Understanding what each thickness level offers will help you make an informed decision that leads to better sleep quality.

Understanding Thickness Categories

Mattress topper thickness can be broadly categorised into three main groups, each serving different purposes and sleeper profiles.

Thin Toppers (2.5cm to 5cm)

Thin toppers are ideal for those who need only minor adjustments to their existing sleep surface. They work best when your current mattress is in good condition but you want to add a touch of softness or a specific feature like cooling properties. These thinner options are also excellent for guest beds, children's rooms, or situations where you don't want to significantly alter the height of your bed.

Budget-conscious buyers often gravitate toward thinner toppers as they're more affordable. However, if you're experiencing genuine discomfort or your mattress has noticeable wear, a 5cm topper may not provide sufficient improvement.

Medium Toppers (5cm to 8cm)

This is the sweet spot for most Australian sleepers. A 7cm or 8cm topper provides substantial comfort enhancement while maintaining the supportive qualities of your underlying mattress. If you're looking to address moderate pressure point issues, add meaningful cushioning for side sleeping, or extend the life of an ageing mattress, this thickness range typically delivers the best results.

Medium-thickness toppers also work well for couples with slightly different firmness preferences. The additional depth allows the topper to contour more effectively to individual body shapes while still providing consistent support across the entire sleep surface.

Thick Toppers (8cm to 12cm)

Thick toppers essentially transform your existing mattress into something entirely new. They're the right choice when your mattress is significantly worn, too firm for your liking, or when you have specific health requirements that demand maximum pressure relief. People with chronic back pain, arthritis, or fibromyalgia often benefit from thicker toppers that provide comprehensive body contouring.

However, thicker isn't always better. Very thick toppers can make it harder to move around in bed, may retain more heat, and can create accessibility challenges for older individuals or those with mobility issues. The added height also means you might need to adjust your bedding and consider whether your fitted sheets will still fit properly.

Factors That Influence Your Ideal Thickness

Body Weight Considerations

Your body weight plays a crucial role in determining the optimal topper thickness. Heavier individuals typically need thicker toppers because they compress the material more deeply. A person weighing 100kg or more may find that a 5cm topper compresses to only 2-3cm under their weight, significantly reducing its effectiveness.

Conversely, lighter sleepers weighing under 65kg may find thick toppers too plush, potentially causing spinal misalignment. For these individuals, a medium 5-7cm topper often provides ideal comfort without excessive sinkage.

Sleep Position Matters

Your preferred sleep position significantly affects how much cushioning you need. Side sleepers require more pressure relief at the shoulders and hips, meaning they typically benefit from thicker, softer toppers in the 7-10cm range. The additional depth allows the topper to cradle these pressure points effectively.

Back sleepers generally need less thickness because their weight distributes more evenly across the surface. A 5-7cm topper usually provides sufficient comfort while maintaining proper spinal alignment. Stomach sleepers require the least cushioning—typically 5cm or less—as too much softness can cause the pelvis to sink and create lower back strain.

Current Mattress Condition

The state of your existing mattress should influence your thickness choice substantially. If your mattress is relatively new but simply too firm, a thinner 5cm topper can soften the surface without dramatically changing its character. However, if your mattress shows visible sagging, has noticeable body impressions, or has lost significant support over the years, you'll need a thicker topper to compensate.

Keep in mind that a mattress topper cannot fix a severely deteriorated mattress. If your mattress sags more than 3-4cm in any area, no topper thickness will restore proper support—you'll need a new mattress instead.

Material Density and Its Relationship to Thickness

Thickness alone doesn't tell the whole story. The density of your topper material affects how it performs at any given thickness. A high-density 5cm memory foam topper (60kg/m³) may provide better support than a low-density 8cm topper (35kg/m³) because the denser foam resists compression more effectively and maintains its supportive properties longer.

When comparing toppers, always consider both thickness and density together. Australian climate conditions, particularly our warm summers, also mean that thicker memory foam toppers may retain more heat. If you choose a thick memory foam option, look for cooling gel infusions or open-cell structures that promote airflow.

Practical Considerations

Before finalising your thickness choice, consider these practical factors:

• Bed height: Adding a 10cm topper significantly raises your sleeping surface, which may affect how easily you get in and out of bed
• Sheet fit: Ensure your fitted sheets have deep enough pockets to accommodate the extra depth
• Bed frame compatibility: Very thick toppers may interfere with headboards or create an unusual mattress-to-frame proportion
• Partner considerations: If sharing a bed, ensure both sleepers are comfortable with the chosen thickness

Making Your Final Decision

For most Australians seeking noticeable improvement in sleep comfort, a 7-8cm topper represents the optimal balance of comfort enhancement, value for money, and practical usability. This thickness provides meaningful pressure relief without the drawbacks of very thick options, works well across different body types when appropriately dense, and fits comfortably with standard bedding.

If budget constraints are a concern, prioritise density over thickness—a quality 5cm topper with 50kg/m³ density will outperform a cheap 10cm option with 35kg/m³ density every time. And remember, the best thickness for you ultimately depends on your unique combination of body weight, sleep position, mattress condition, and personal comfort preferences.