How thick should a mattress be? An expert's guide to picking the right height

What do you look for when buying a new mattress? The obvious answer would be price, firmness and comfort, but many people would also likely look at the materials used.

You'll also notice that the best mattresses in Australia come in a range of heights, and this one criterion is easy to overlook as not being important. In fact, mattress thickness determines how it feels and performs, making it quite an important aspect to look into when shopping for a new bed.

So, is there a particular thickness a mattress should be for the best sleep? It's not really a one-size-fits-all scenario, so we've put together this guide to explain the different thickness categories and which ones would suit each kind of sleeper.

While thick mattresses tend to cost more due to all of the materials they use, you'll be able to save money by taking advantage of this month's mattress sales.

Mattress thickness chart

Here's a brief rundown of the most common mattress thickness levels and who (and what sleep scenarios) they are best for:

What determines mattress thickness?

The thickness of a mattress is determined by its construction.

Every mattress has two main components — a comfort system and the support layer. Each of these are made up of layers, and the more there are, the thicker (or taller) the mattress will be.

The support core is the base of the mattress, providing stability and support to the sleeper. In most mattresses, this component can make up at least half the mattress' height, ranging about 10cm to 25cm.

The comfort layer is what you feel when you lie down, designed to cushion the body by contouring around it, but without creating pressure points. Depending on the mattress type, this component is made of multiple layers, typically made from memory foam, latex or soft polyfoam. Some mattresses also use natural materials like wool or cotton. Comfort layers can be about 2cm to 4cm.

There are some thick mattresses that also feature a 'transition' layer, which separates the support core from the top comfort system. This layer is usually made from firmer foam or latex. Transition layers can add about 3cm to 8cm more thickness.

How to choose the right mattress thickness

Just because a mattress is extra thick, doesn't mean it's the best option for you. Once you understand what the different thickness options mean, you'll be able to make better choices for your new bed.

Keep the following criteria in mind when choosing the right mattress thickness for your needs. That said, it's important to note that the below information isn't set in stone — mattress choice is very subjective and personal, which is why the free trial periods that most mattress-in-a-box brands offer is important.

1. Sleeping position

Are you a side, back or front sleeper (or a little bit of each)? How you fall into bed at night and wake up in the morning will determine how thick or thin your mattress should be:

• Side sleepers benefit most from a thicker mattress (30cm to 35cm) with multiple comfort layers to alleviate pressure from their shoulders and hips.
• Back sleepers should fare well with a standard mattress height (25cm to 30cm) that keeps their spine aligned while relieving pressure from their lower back.
• Stomach sleepers can opt for a mattress that skews thinner (25cm) to keep their hips upright.
• Combination sleepers are best suited to a mattress with a standard thickness (30cm) to comfortably accommodate any position.

2. Body Weight

Choose a mattress thickness that can comfortably support your weight. Anything too firm or soft will result in unpleasant aches in the morning:

• Lightweight sleepers (under 60kg) will want to look for a tall mattress (at least 30cm) with multiple plush comfort layers.
• Average-weight sleepers (60kg to 105kg) should be fine with a standard-height mattress (25cm to 30cm) with a medium-firm feel. This will depend on your main sleep position and the construction of the mattress.
• Heavier sleepers (over 105kg) will need a tall mattress (30cm to 35cm) with at least a 15cm base layer and thicker comfort layers for maximum contouring and support.

3. Health conditions

If you suffer from joint or back aches, or have limited mobility, using a tall mattress might not be the best option for you. You should be able to sit at the edge of your bed with your feet flat on the ground and knees bent at a 90º angle.

Anything too tall or short will make it difficult to get in and out of bed in the morning, especially if you have limited mobility. However, if a taller mattress makes more sense based on other factors, adding a set of bedside steps could help.

4. Sleeping arrangements

Thicker mattresses can handle more weight. If you're sharing a bed with a partner, your kids, and/or your pets, look for a mattress that's at least 30cm thick. Anything thinner will wear out sooner.

5. Size of your bedroom

A thick mattress will fit nicely in a palatial space, but in a smaller room, it could make you feel claustrophobic. Also consider your bed frame — if you have an adjustable bed or a basic (platform) frame, a thick mattress may not work.

Which mattress thickness should you buy?

Most adults should fare well with a standard mattress height (25cm to 30cm), but if you want to go taller or shorter, here's what we recommend.

Buy a thicker mattress if...

✅ You're a side sleeper: Most of the best mattresses for side sleepers skew taller as they're loaded with comfort foams to relieve pressure in the shoulders and hips.

✅ You're over 105kg: Thicker beds boast more layers and taller support cores.

✅ You share a bed: Whether you're sharing a bed with one person or as a family, thicker mattresses can withstand more weight than thinner ones.

Buy a thinner mattress if...

✅ You have mobility issues: A thinner mattress will not only be easier for you to get in and out of, but it'll be easier to move and rotate with limited assistance.

✅ You have a small bedroom: Tall mattresses just don't look good in a tiny bedroom. A mattress on the smaller side of standard should work.

✅ You want to save money: Thicker mattresses use more materials, and that's reflected in their pricing. Going for a bed that's not too lofty is one way to keep some cash in your wallet.