Best Mattress for a Day Bed

The best mattress for a day bed is a medium-firm, 10 to 15 cm thick all-foam or pocket-spring model in a single (92 × 188 cm) or king single (107 × 203 cm) size, depending on your day bed frame. 

Foam suits day beds used more as seating; pocket springs suit day beds used more for regular sleep. If your day bed includes a trundle underneath, the trundle mattress usually needs to be thinner (7 to 12 cm) so it fits under the main frame. Below we cover thickness, firmness, foam vs spring, sizing and trundle considerations.

Key Takeaways

• The best day bed mattress is medium-firm and 10 to 15 cm thick, thin enough to slide under a day bed frame edge but thick enough for genuine sleep comfort.

• Foam works best for day beds used mostly as seating because it compresses evenly and returns to shape; pocket spring works best for day beds used mostly for regular sleep.

• Standard day bed sizes are single (92 × 188 cm) and king single (107 × 203 cm), matching AU mattress sizing so you can use standard sheets.

• Trundle mattresses need to be 7 to 12 cm thick to fit under the main day bed frame; thicker options won't slide out.

• Day beds are comfortable for everyday sleep if the mattress is right, though they're generally less spacious than a full bed frame and better suited to solo sleepers.

What to Look for in a Day Bed Mattress

A day bed mattress needs to work as both a sofa cushion and a sleep surface, which means the choice is different from a standard bedroom mattress. Prioritise thickness that suits your frame, firmness that supports sitting without feeling like a couch cushion at night, and a construction (foam or pocket spring) that matches your usage split between sitting and sleeping. Below we cover each.

Thickness & Firmness for Sitting and Sleeping

Day bed mattresses typically sit at 10 to 15 cm thick, which is 5 to 15 cm thinner than a standard bedroom mattress (20 to 25 cm). This thickness range balances two needs: thick enough to give real support for sleeping, thin enough to slide under a day bed's back cushion or against a frame edge without looking bulky. Anything under 10 cm feels like a sofa cushion; anything over 15 cm can make the day bed look overstuffed and be hard to fit standard fitted sheets around.

Medium-firm is the best firmness for a day bed because it handles both sitting and sleeping. Soft mattresses compress too much when you sit at the edge and sag over time; firm mattresses feel too hard for sitting comfort. Medium-firm gives you enough support for sleep across a range of positions and enough resilience for daily sitting without breaking down. If you're using the day bed almost exclusively for sleep and rarely as seating, you can size up to a firmer feel; if it's mostly seating, stay in the medium-firm range.

Foam vs Pocket Spring

All-foam day bed mattresses are the most common and generally the better choice for dual use (sitting + sleeping). Foam compresses evenly under seating pressure and returns to shape without permanent indent, so a day bed used daily as a couch won't develop the "sitting spot" divot that a spring mattress can. Foam is also lighter, easier to lift for cleaning underneath, and better with trundle designs where the mattress may need to slide in and out.

Pocket-spring day bed mattresses suit day beds used primarily for regular sleep, especially if the sleeper prefers a springier, more responsive feel. The trade-off is that pocket springs compress unevenly under sustained seating (the front edge where you sit takes disproportionate load), so a day bed used daily as a couch is a harder job for pocket-spring construction. If you go pocket spring, choose a design with edge-support reinforcement.

For most day beds, our mattress range is the practical pick, engineered with adaptive open-cell foam that handles both sitting and sleeping without breaking down. 

Day Bed Mattress Sizes Compared

Day bed mattresses in Australia typically follow single (92 × 188 cm) or king single (107 × 203 cm) sizing to match standard mattress dimensions. Trundle mattresses that pull out from underneath are usually the same width as the main day bed mattress but thinner to fit under the frame. The table below covers standard sizes and their use cases.

Standard fitted sheets in the corresponding bed size will fit a day bed mattress, provided the mattress falls in the standard AU dimension range. If your day bed uses a mattress under 10 cm thick, standard fitted sheets can be loose; look for shallow-pocket sheets designed for slimmer mattresses.

Trundle & Pull-Out Mattress Considerations

A trundle mattress is the additional pull-out mattress that sits under a day bed frame, and it typically needs to be 7 to 12 cm thick to fit in the storage space underneath. This makes trundle mattresses noticeably thinner than the main day bed mattress, which affects comfort: a 7 cm trundle is more of an occasional-guest surface than a nightly-sleep option.

Practical trundle considerations:

• Measure the clearance underneath the main day bed frame. This gives you the maximum trundle mattress thickness. Add 2 to 3 cm of buffer so the trundle slides in and out without scraping.

• Match trundle mattress width to the main mattress. Most trundle designs use the same width as the main mattress (single width), so both bed surfaces are consistent when both are used together.

• Choose foam over spring for trundles. Foam is lighter (easier to lift), thinner in equivalent support (better for tight clearance), and more compression-tolerant when stored under weight.

• Look for trundle mattresses on wheels. Pull-out access is much easier with a wheeled or castor-mounted trundle base, especially for daily use.

• Consider a mattress protector. Trundle mattresses collect more dust from floor-level storage. Our mattress protectors keep the surface fresh between uses. 

If a trundle setup feels like more furniture than you actually need, a compact sofa bed is often a more flexible alternative. Our Wanda Sofa Bed works well in studios and one-bed apartments where a day bed with trundle would otherwise dominate the room.

Are Day Beds Comfortable for Everyday Sleep?

Day beds are comfortable for everyday sleep if the mattress is genuinely supportive and the frame is properly rated, though they're generally more suited to solo sleepers than couples. The mattress is doing more work than a standard bedroom setup because it also acts as seating, so choosing a proper 10 to 15 cm mattress in medium-firm rather than an off-the-shelf sofa cushion makes the difference between "acceptable spare bed" and "genuinely comfortable everyday sleep".

The main comfort trade-offs of day beds compared to a full bed frame:

• Width. Day beds are single or king single, so two adults sharing regularly is impractical.

• Backboard geometry. Some day beds have three-sided frames (back plus two sides), which can feel enclosed or catch limbs during the night if you move a lot.

• Trundle noise. If the trundle isn't stored correctly or the frame flexes, movement during sleep can be noisier than a solid bed base.

• Cooling. Day beds sit lower to the ground than platform bed bases in many designs, which can affect airflow underneath and cooling.

If you're using a day bed as the primary sleep setup for one person (in a studio, tiny room, or as part of a share-house configuration), the mattress choice matters more than any other factor. Prioritise a quality medium-firm foam or hybrid mattress in the appropriate size, and the day bed handles nightly sleep well. For occasional guest use, a slightly thinner mattress is often fine.

Explore Our Mattress and Sofa Bed Range

If a day bed doesn't quite fit your setup, our mattress and sofa bed ranges cover the same dual-use logic in different forms. 

Explore our range:

• Mattress: all-foam Kloudcell® construction for pressure relief and airflow, in Australian sizes single to king, backed by our 120-night trial and 10-year mattress warranty. Winner of ProductReview Mattress of the Year 2023, 2024, and 2025, a three-year streak.

• Compact sofa bed: the Wanda Sofa Bed 2nd Gen, designed for studios and one-bed flats where a day bed with trundle would otherwise take up too much space.

• Convertible flip-bed sofa: the Koala Sofa Bed 4th Gen with the FlipBed™ mechanism, tool-free assembly and our 120-night trial, for larger dual-purpose setups.

• Sofa beds: dual-purpose furniture designed to work as both seating and proper sleep surface.

• Mattress protectors: breathable, waterproof-backed protectors that keep day bed and trundle mattresses fresh between uses.