Mattress Thickness Guide: How Thick Should a Mattress Be?
Most adult mattresses are about 20 to 30 cm (8 to 12 in) thick. Thinner suits bunk beds and daybeds; 25 to 30 cm gives more cushioning for most adults. A thicker mattress also raises the bed and needs deep-pocket sheets.
Key takeaways
- Most adult mattresses are 20 to 30 cm (8 to 12 in) thick.
- Thinner (15 to 20 cm) suits bunk beds, daybeds and toddler beds.
- 25 to 30 cm gives deeper cushioning that many adults prefer.
- Thickness is not firmness: a thick mattress can feel soft or firm.
- Check the sheets, bed height and guardrails before you buy a thick mattress.
How thick should a mattress be?
For most adults, a mattress about 20 to 30 cm (8 to 12 in) thick works well. Thinner mattresses of about 15 to 20 cm suit bunk beds, daybeds and toddler beds, while 25 to 30 cm gives the deeper cushioning many adults prefer. Thickness is not the same as firmness, so choose the feel first, then check that the thickness suits your bed, your sheets and anyone climbing in and out.
Mattress thickness chart
| Thickness | Inches (approx.) | Usually suits |
|---|---|---|
| 15 to 20 cm | 6 to 8 in | Bunk beds, daybeds, toddler beds and occasional guest beds |
| 20 to 25 cm | 8 to 10 in | Children, teens and lighter adults |
| 25 to 30 cm | 10 to 12 in | Most adults, couples and side sleepers who like more cushioning |
| Over 30 cm | Over 12 in | People who want a very plush feel or a tall, hotel-style bed |
These are general ranges, not rules. What matters most is how the mattress supports you, which our guide to choosing a mattress covers by sleep position.
What does thickness change?
- Comfort layers: a thicker mattress usually has more room for cushioning on top of the support core.
- Bed height: the mattress adds to the height of the base. Sit on the edge: your feet should rest flat on the floor with your knees at about hip height.
- Sheets: a thick mattress needs deep-pocket fitted sheets.
- The headboard: a thicker mattress covers more of the headboard, so a low headboard can almost disappear. Our headboard guide explains how to choose one.
- Weight and handling: thicker mattresses are heavier to rotate and move.
Which thickness suits you?
- Side sleepers often like a thicker mattress with more cushioning for the shoulders and hips.
- Heavier sleepers usually benefit from a thicker mattress that gives more support before they reach the core.
- Children need a mattress that fits the frame snugly; for a young child, think about how high the sleeping surface is.
- Bunk beds need the thickness the maker recommends. Health Canada advises that top-bunk guardrails stand at least 12.7 cm (5 in) above the mattress, so too thick a mattress makes them unsafe. See our kids bed safety checklist.
- People with limited mobility may prefer a bed height that is easy to sit on and stand up from.
Thick or thin: the pros and cons
| Factor | Thicker (25 cm and up) | Thinner (under 20 cm) |
|---|---|---|
| Cushioning | More room for comfort layers | Less cushioning; can feel firm |
| Look | Full, hotel-style bed | Low, simple profile |
| Bed height | Higher; easier to sit on for many adults | Lower; suits small children and bunks |
| Sheets | Needs deep-pocket fitted sheets | Standard fitted sheets |
| Handling | Heavier to rotate and move | Lighter and easier to move |
What sheets fit a thick mattress?
Measure the mattress from the bottom edge to the top, then choose a fitted sheet with a pocket depth of at least that much. For a 30 cm mattress, look for a pocket of at least 30 cm (about 12 in), and allow more if you add a topper or a padded protector. Size matters too: metric mattresses need metric sheets, as our European vs Canadian bed size guide explains.
Shop the look
Our mattresses are 30 cm thick
All three of our mattresses are 30 cm (about 11.8 in) thick: the 90 x 200 cm single, the 120 x 200 cm and the 180 x 200 cm king. That is a generous, high-profile thickness that gives a full look on the bed and plenty of cushioning. Use deep-pocket fitted sheets, and ask us if you plan to use one on a bed with guardrails. When the time comes, our guide on when to replace your mattress lists the signs. See all our mattresses.
See the thickness in person in Hamilton
Sit on the edge and lie down on our mattresses at Home Centre Green, 110 Lancing Dr, Unit 2, Hamilton, ON L8W 3A1, with free parking outside.
We are open Monday to Friday 9:00 am – 6:00 pm and Saturday 10:00 am – 5:00 pm. We are closed on Sundays. Call or WhatsApp us on (905) 253-0202, or send us a message.
Frequently asked questions
How thick should a mattress be?
For most adults, a mattress about 20 to 30 cm (8 to 12 in) thick works well. Thicker mattresses usually have more comfort layers, which many people like, especially heavier sleepers and side sleepers. Thinner mattresses suit children, bunk beds and daybeds. How it feels matters more than the number.
Is a 30 cm mattress too thick?
Not for most beds. At about 11.8 inches, 30 cm is a generous, high-profile thickness that gives a full look and plenty of cushioning. Check that you can sit on the edge with your feet flat on the floor, that your fitted sheets are deep enough, and that it suits any guardrails on the bed.
Does a thicker mattress mean it is more comfortable?
Not always. Thickness usually means more layers, but comfort depends on what those layers are and how firm they feel. A well-made 20 cm mattress can be more comfortable for you than a poorly made 30 cm one. Lie on a mattress in your usual position before you decide.
What thickness of mattress is best for a bunk bed?
Use the thickness the bunk bed maker recommends, usually a thinner mattress. Health Canada advises that the top of the top-bunk guardrails sits at least 12.7 cm (5 in) above the mattress, so a mattress that is too thick can make the guardrails too low to be safe.
What sheets fit a 30 cm mattress?
Choose deep-pocket fitted sheets with a pocket depth of at least 30 cm (about 12 in), and a little more if you add a topper or a thick protector. Check the size too: a 90 x 200 cm mattress needs European single sheets, not Canadian twin sheets.
Home Centre Green Design Team
The team behind our Hamilton showroom. We help customers choose Turkish-made sofas, beds and carpets every day, and we write these guides to answer the questions we hear most in store.
