Mattress shopping is one of those tasks that seems straightforward until you’re actually in the process of choosing one. Everyone pays attention to firmness, materials, cooling properties, coils, and foams. But one of the most decisive factors mattress thickness is almost always overlooked. The height of a mattress is far more than a number on the label. It influences how the bed feels, how well it supports your spine, how easy it is to get in and out of, the longevity of the mattress, and even how it works with your existing bed frame.
If you’ve ever had a mattress that felt too hard, too soft, too wobbly, or simply uncomfortable over time, the issue may not have been firmness at all it may have been thickness. Mattress height decides the distribution of your body weight, the depth of cushioning beneath you, and how the mattress performs over the years. Choosing the wrong thickness is one of the most common reasons people wake up tired, stiff, or unsupported making it essential to explore our mattress collection before making a decision.
This comprehensive guide explores everything you need to know about mattress thickness, helping you understand what height suits your sleeping style, body weight, comfort preferences, and bedroom setup.
Why Mattress Thickness Deserves Serious Attention
A mattress is made of layers base support layers, comfort layers, transition layers, and sometimes additional pillow tops. These layers vary in density, firmness, elasticity, and durability. Thickness determines how effectively these layers can perform.
1. Thickness Influences Comfort and Pressure Relief
A thin mattress cannot absorb pressure adequately, especially at the shoulders, hips, and lower back. A thicker mattress, with deeper cushioning layers, spreads body weight more evenly. This makes a dramatic difference for side sleepers, heavier sleepers, and anyone with joint sensitivity.
2. Thickness Affects Spinal Alignment
When your mattress is too thin, your hips or shoulders may sink disproportionately, causing the spine to bend unnaturally. Over time, this leads to morning stiffness, lower back pain, and sleep disruptions. A mattress of the correct thickness keeps your spine neutral regardless of sleeping position.
3. Thicker Mattresses Last Longer
One thing people underestimate is durability. Thin mattresses wear out faster because the comfort layers compress. Thicker mattresses distribute pressure across multiple layers, reducing long-term sagging. They also tolerate the weight of two sleepers better than thin mattresses.
4. Bed Height and Accessibility
Most people feel most comfortable when the top of their mattress sits at knee height. This makes sitting, standing, and turning easier. A mattress that’s too thick (or too thin) can make the bed uncomfortable to use daily, especially for seniors or anyone with mobility issues.
5. Aesthetic and Fit on Bed Frames
A mattress that’s too thick may overpower a minimalist bed frame or look bulky. A mattress that’s too thin may look sunken or underwhelming. Thick mattresses generally pair beautifully with solid slat frames, while thinner mattresses work better with bunk beds and adjustable frames.
Mattress Thickness Categories and What They Really Mean
Not all mattresses are created equal, and thickness dictates how the bed feels and functions. Here is a detailed breakdown of standard thickness ranges.
Thin Mattresses (12–18 cm)
These mattresses are compact and typically firm. They offer minimal contouring and are primarily designed for lightweight users or temporary use.
Where thin mattresses make sense:
-
Children’s rooms (kids weigh less and need firmer surfaces)
-
Bunk beds (thicker mattresses compromise safety rails)
-
Trundles or pull-out beds
-
Sleepovers or occasional guest rooms
-
Rental properties or holiday homes
Thin mattresses don’t provide enough depth for long-term adult use, especially for side sleepers or people with body aches.
Standard Mattresses (20–25 cm)
This is the thickness range most New Zealand households prefer. Standard mattresses provide a solid balance of comfort, support, and affordability.
Why they work so well:
-
Suitable for all bed frames
-
Provide enough cushioning without excessive height
-
Compatible with storage beds and adjustable beds
-
Durable enough for everyday adult use
These mattresses often include multiple layers: a supportive base, a transition layer, and a comfort topper.
Thick Mattresses (28–35 cm)
These mattresses offer premium comfort, significantly deeper cushioning, and enhanced support systems. They feel luxurious and are often compared to mattresses in high-end hotels.
What thick mattresses offer:
-
Superior pressure relief
-
Better motion isolation for couples
-
Stronger support for heavier sleepers
-
Long-lasting structural integrity
-
A plush, enveloping feel
If you enjoy a mattress that hugs your curves and feels indulgent, this range is ideal.
Extra-Thick Mattresses (36–40+ cm)
These mattresses represent the highest level of cushioning and support available. They typically feature advanced foam technologies, reinforced coil systems, and extensive quilting or pillow tops.
Who should consider extra-thick mattresses:
-
People with chronic pain needing maximum support
-
Heavier individuals needing deep, stable comfort
-
Homeowners wanting a luxury bed that feels extravagant
-
Master bedrooms with high bed frames
These mattresses are heavy and may require deep-pocket sheets, but the comfort payoff is significant.
Choosing Mattress Thickness Based on Sleeping Position
Your sleeping position is the biggest factor that should guide mattress thickness.
Side Sleepers
Side sleepers require extra cushioning because their weight rests on narrower pressure points.
Ideal thickness: 28–35 cm
A thicker mattress prevents the shoulders and hips from pressing too deeply against a firm base.
Back Sleepers
Back sleepers need uniform support and a mattress that encourages natural spinal curvature.
Ideal thickness: 25–30 cm
This range supports the lumbar area while providing enough comfort on the surface.
Stomach Sleepers
This position places pressure on the pelvis and lower spine, making excessive softness a problem.
Ideal thickness: 20–28 cm
A slightly thinner, firmer mattress keeps the spine aligned.
Combination Sleepers
Those who alternate between side, back, and stomach positions need balanced support.
Ideal thickness: 25–32 cm
A mattress that’s too thin won't offer cushioning, and one that's too thick can feel restrictive.
Choosing Mattress Thickness by Body Weight
Your body weight changes how far you sink into the mattress. Thickness must match your frame.
Lightweight Sleepers (Under 60 kg)
Light sleepers don’t compress mattresses as deeply.
Ideal thickness: 20–28 cm
Average Weight Sleepers (60–100 kg)
This category includes most adults.
Ideal thickness: 25–33 cm
Heavyweight Sleepers (100+ kg)
Heavier bodies need more structure, thicker layers, and reinforced support.
Ideal thickness: 30–38 cm
Without enough thickness, heavier sleepers experience sagging and discomfort quickly.
How Bed Frame Type Influences Mattress Thickness
Your bed frame isn’t just a base it affects how the mattress performs.
Platform Beds
Compatible with all mattress heights, but very thick mattresses may sit too tall.
Recommended thickness: 20–33 cm
Slatted Frames
Work best with medium-to-thick mattresses. Thin mattresses may feel too firm.
Recommended thickness: 25–35 cm
Drawer Storage Beds / Gas-Lift Beds
Very thick mattresses can make lifting difficult or unbalanced.
Recommended thickness: 22–30 cm
Adjustable Beds
Require flexibility, so avoid overly thick mattresses.
Recommended thickness: 20–28 cm
Bunk Beds
Safety rail height limits mattress thickness.
Recommended thickness: 12–18 cm
Matching Thickness to Specific Users
Every group has unique needs. Here’s a quick guide:
Children:
15–20 cm (firmer, easier to climb)
Teenagers:
20–28 cm (growing bodies need cushioning)
Adults:
25–35 cm (most comfort + durability)
Couples:
28–35 cm (motion isolation + edge support)
Seniors:
20–30 cm (comfortable height for mobility)
How to Determine Your Perfect Thickness
Use this checklist:
1. Consider your sleeping position
Side sleepers → Thick
Back sleepers → Medium
Stomach sleepers → Medium-Thin
2. Factor in your body weight
Heavier = thicker
Lighter = standard
3. Check your bed frame height
Your feet should touch the floor comfortably when sitting.
4. Think long-term
Thicker mattresses resist wear better, especially for couples.
Final Thoughts: What Thickness Works Best for Most NZ Homes?
Most New Zealand adults will be happiest with a mattress between 25 and 35 cm.
This range delivers the best balance of cushioning, support, and longevity without being too tall or difficult to manoeuvre.
The right mattress thickness can transform the way you sleep supporting your spine properly, easing pressure, and helping you wake up refreshed instead of sore or stiff.