Bringing home a new baby means lots of decisions, and the cot mattress is one of the most important. The right mattress supports safe sleep and helps your little one feel settled, even when nights are still a bit broken. This gentle infant mattress guide is here to help you focus on what really matters, so choosing the best newborn mattress feels clear rather than confusing.
Standard AU cot mattress: 132x70cm. Compact cot mattress: 119x65cm. The mattress must fit with no gap larger than 25mm on any side, an AS/NZS 2172:2003 requirement. Bassinet mattresses are a separate size again at 80x41cm, listed across the bassinets and cradles range.
You don't need to be an expert in materials or testing standards to make a good choice. If you understand firmness, fit, and everyday care, you're most of the way there. From there, you can look at design details that support baby sleep comfort, fit your cot, and work well in your home.
The mattress does more for sleep safety than almost anything else in the cot. Firmness, fit and breathability matter in that order, and getting the first two right removes most of the risk before comfort is even a consideration. If you are choosing the cot at the same time, our guide to setting up a baby nursery covers the wider room plan.
Why Does the Cot Mattress Matter So Much for Baby Sleep Safety?
Because a baby spends 12 to 16 hours a day on it, and because a soft or poorly fitting surface is one of the few genuine sleep risks a parent can control entirely. Red Nose Australia names a firm, flat, well-fitting mattress as a primary safe sleep requirement.
A mattress that moulds around a baby's head when pressed is too soft, regardless of what the label claims. Press with a flat palm when it arrives, the surface should spring back immediately and feel consistent from end to end.
Fit matters as much as firmness. A gap at the side of a cot mattress is a trap for an arm or a leg, and it is the failure that happens when a mattress is bought separately from the frame without checking the dimensions.
Measure the inside of the cot frame rather than the outside, and check both diagonals. A frame assembled slightly out of square will read correctly on one measurement and short on the other, which is how a mattress that looked right on paper arrives leaving a gap at one corner.
What Does AS/NZS 8811.1:2013 Mean for Australian Baby Cot Mattresses?
AS/NZS 8811.1:2013 is the Australian firmness test for infant sleep surfaces. It measures how far a mattress compresses under a defined load, a mattress that passes is firm enough that it will not conform around a baby's face.
It sits alongside AS/NZS 2172:2003, which governs the cot frame and includes the 25mm maximum gap between mattress and frame. Both apply to a cot sleep setup, and neither substitutes for the other. Options across the baby mattress range are tested to the firmness standard and sized to Boori cot frames exactly.
A second-hand mattress is the one case where the standard cannot help you. Compression is permanent and invisible, and the hygiene history is unknown, Red Nose Australia recommends against using one for a new baby.
Thickness is capped as well as fit. A mattress deep enough to reduce the effective cot side height below the safety guideline is the wrong mattress for that cot, regardless of how well it fits the footprint, always check the maximum the cot manufacturer specifies.
How Do I Know Which Cot Mattress Size I Need in Australia?
Match the mattress to the cot model rather than assuming a close size will fit. Australian sizes are fixed by format.
| Mattress type | AU size | Fits |
|---|---|---|
| Standard cot mattress | 132 x 70cm | All Boori standard cots, the most common size in Australia |
| Compact cot mattress | 119 x 65cm | All Boori compact cots, smaller nurseries and apartments |
| Oval cot mattress | ~119 x 64cm | Boori-specific oval size, not interchangeable |
| Bassinet mattress | 80 x 41cm | Boori Tidy Bassinet |
Australian sizes differ from UK and European ones. A common UK cot mattress is 120x60cm, which will not correctly fit an Australian standard cot at 132x70cm. Never use a mattress sized for another country's cots. Sizing for the cot range is listed on each product page, and our guide to choosing the perfect baby cot covers the frame side of the decision.
Order the mattress at the same time as the cot. It removes the compatibility question entirely, and both arrive together for a single setup. If the cot is a convertible model, the same mattress carries through to the toddler bed stage.
What Is Inside a Baby Cot Mattress and What Should I Look For?
The core does the work. Foam, pocket springs, or an airflow structure, each behaves differently under two to three years of daily use, and the cover is a secondary consideration.
Look for a removable or wipeable cover, evenly finished edges with no loose stitching, and a construction that states what it is made from rather than describing it vaguely. Clear labelling is usually a proxy for a manufacturer who has tested the product.
Weight is a practical detail worth noting. A heavier mattress is harder to lift for sheet changes, which in the newborn months you will be doing far more often than you expect.
Foam, Pocket Spring, or Airflow, Which Cot Mattress Is Best for Australian Conditions?
Cot mattress types best for Australian conditions:
Foam mattress: Lightest and lowest cost. Suited to compact cots, travel use, and budget-conscious families. Good firmness when new, but can compress over 2–3 years of daily use. Best for compact cots and families wanting portability.
Pocket spring mattress: Each spring moves independently, maintaining even firmness across the surface over 2–3 years. Heavier and more expensive than foam, and includes air circulation through the spring gaps. Best for standard cots and long-term use.
Airflow or 3D breathable mattress: Perforated or 3D mesh construction allows maximum air circulation and reduces overheating risk. Especially suited to Queensland, northern NSW and WA, where nursery temperatures can stay high overnight even with air conditioning running.
Red Nose Australia recommends a nursery temperature of 16–20°C. In warmer Australian climates, an airflow mattress combined with a light fitted sheet reduces the need for overnight cooling. All three types can be safe when they meet AS/NZS 8811.1:2013 and fit the cot correctly, their safer sleep guidance covers the room conditions alongside the sleep surface.
Price tends to track construction rather than brand. Foam sits at the lower end, pocket spring in the middle, and airflow at the top, and across two to three years of nightly use the difference per year is smaller than the headline gap suggests.
How Does Mattress Breathability Help in Australian Climates?
Air moving through the mattress core carries heat and moisture away from the sleep surface rather than holding it against the baby. Through a humid Queensland or northern NSW night, that difference is noticeable.
Pair a breathable core with breathable bedding. Cotton and bamboo-derived fabrics across the baby bedding range handle humid nights better than synthetic blends, and a fitted sheet is all that goes over the mattress for babies under 12 months.
Good airflow around the cot matters too. A slatted base lets air move underneath, and leaving the bed unmade for an hour each morning lets any overnight moisture escape before the sheet goes back on.
How Do I Care for a Baby Cot Mattress?
Use a waterproof protector from the first night, rotate the mattress every two to three months, and vacuum the surface occasionally to lift dust.
A protector takes the wear that would otherwise reach the mattress core, and it is the single accessory that most extends useful life. Keep two in rotation so one is always clean.
Rotating end to end distributes wear evenly so the surface stays level. In humid seasons, ventilation around the cot helps the core stay dry. Our guide to baby hardware and accessories covers what else is worth having on hand.
How Do I Make My Baby Comfortable on a Firm Cot Mattress?
Comfort comes from room conditions and sleepwear, not from a softer mattress. Red Nose Australia recommends a nursery temperature of 16–20°C, a fitted sleep suit, and a sleeping bag in a tog rating matched to the season.
Tog choice varies by state. In Queensland and northern NSW, a 0.5–1.0 tog bag suits most of the year. In Victoria, the ACT and Tasmania, a 2.5–3.5 tog suits winter with a lighter option for summer. Buying two, one light, one warm, covers the full Australian year in most of the country.
A firm surface is not an uncomfortable one for a newborn. Babies have not yet developed the preference for softness that adults have, and a firm mattress supports the spine evenly across the whole body.
What Are the Final Checks Before I Order a Baby Cot Mattress in Australia?
Six checks before ordering:
- Confirm the cot model and its internal frame dimensions.
- Match the mattress size exactly, 132x70cm standard, 119x65cm compact.
- Check the mattress states compliance with AS/NZS 8811.1:2013.
- Confirm the gap will be no wider than 25mm on any side.
- Check the maximum mattress thickness the cot manufacturer specifies.
- Order a waterproof protector at the same time.
Replace a cot mattress when the surface shows permanent compression, when it has been heavily soiled despite protector use, when the child transitions to a toddler bed, or when it is more than three years old.
FAQs
How do I know which cot mattress to buy in Australia?
Choose a mattress that is firm, flat, and designed specifically for infant use, not a cut-down adult mattress or soft foam. It must fit the cot with no gap larger than 25mm on any side (AS/NZS 2172:2003 requirement). Standard AU cot mattress: 132x70cm. Compact cot mattress: 119x65cm. If you already have a Boori cot, choose from the matching Boori mattress range, as each is designed to fit the cot frame exactly with no guesswork on gap sizing.
How do I pick the right baby mattress in Australia?
The right AU cot mattress balances firmness, fit, breathability, and ease of cleaning. Firmness is the most important factor, the mattress must comply with AS/NZS 8811.1:2013 and must not compress to a soft surface under a baby's weight. Red Nose Australia recommends a firm, flat mattress as a primary safe sleep requirement. In warm Australian climates (QLD, northern NSW, WA), prioritise breathable constructions, airflow or pocket spring, to reduce overheating risk at the recommended nursery temperature of 16–20°C.
What is the difference between foam, pocket spring, and airflow baby mattresses?
A foam mattress is lighter and lower cost, suited to compact cots and budget-conscious families, but can compress unevenly after 2–3 years of daily use. A pocket spring mattress maintains even, firm support across the surface over a longer period, better for standard cots and longer-term use. An airflow or 3D breathable mattress uses a perforated or mesh construction for maximum air circulation, particularly suited to warm Australian climates including Queensland and northern NSW, where nursery overheating risk is higher. All three types can meet AS/NZS 8811.1:2013.
How thick should a baby cot mattress be in Australia?
Most Boori baby cot mattresses are approximately 10–13cm thick, thick enough for firm support without being bulky. The key is not thickness but correct fit: the mattress must sit in the cot with no gap larger than 25mm on any side (AS/NZS 2172:2003). If the mattress is so thick that it reduces the effective cot side height below the safety guideline, it is not the right mattress for that cot. Always follow the cot manufacturer's recommendation for maximum mattress thickness, and order the mattress that is specifically designed for your cot model.
When should I replace a baby cot mattress in Australia?
Replace a cot mattress when: the surface shows permanent compression or indentation that does not bounce back when pressed, the mattress has been heavily soiled despite protector use, the child transitions from cot to toddler bed (the new bed requires a different mattress size), or the mattress is more than 3 years old. Red Nose Australia recommends against using a second-hand cot mattress for a new baby, a second-hand mattress may have compressed unevenly and the hygiene history is unknown. A waterproof mattress protector from day one, rotated regularly, extends useful life within the recommended period.
How to know what cot mattress to buy?
Start by choosing a mattress that is firm, flat, and designed for infant use. Check that it meets relevant safety standards for infant sleep surfaces and that it fits your cot with no large gaps around the edges. Think about how long you want it to last and how easy it is to clean. If you already have a Boori cot, it makes sense to choose from the matching range so you can be confident you're getting the best newborn mattress for that specific frame.
How to pick the right baby mattress?
The right mattress balances safety, comfort, and practicality. A good safe mattress for baby should feel firm to the touch, spring back when pressed, and stay flat and supportive over time. Look at the cover and check if it's breathable and washable. Consider reviews, testing information, and any brand details about compliance with infant firmness standards. Combine these facts with your own baby mattress buying tips list such as weight, cleaning, and cost to narrow down your choice.
What mattress should I buy for a baby cot?
For a baby cot, always choose a mattress that is made for that purpose. Avoid cutting down adult mattresses or reusing soft foam pieces from other products. A purpose-built mattress for newborn will be sized correctly for cot dimensions and designed with infant firmness and ventilation in mind. When in doubt, pair your cot with a mattress from the same brand, as this can make it easier to achieve the best newborn mattress and cot combination for safe sleep.
How thick should a baby cot mattress be?
Most baby cot mattresses are designed to be thick enough to offer strong support without feeling like a bulky adult mattress. There isn't one "perfect" measurement for every cot, but your infant mattress guide should always prioritise firmness, flatness, and correct fit over extra thickness. If a mattress is very thin and feels hard against the cot base, or so thick that it affects cot side height and safety, it may not be suitable. Always follow the cot manufacturer's recommendations on mattress size and height to maintain baby sleep comfort and safety.
