New mattress smell and how to prevent it
The smell is off-gassing from foam, it is strongest in the first 48 hours, and airflow is the only thing that shortens it.
The short answer
Unwrap it, put it in a well-ventilated room, and give it 24 to 72 hours. Most of the smell goes in the first two days and traces can linger a week or two.
It is strongest on foam and boxed mattresses, and mild or absent on natural fillings.
What off-gassing actually is
Polyurethane and viscoelastic foams are made through a chemical reaction, and the finished foam releases small amounts of volatile organic compounds as it cures and airs. That release is what you smell.
It is more noticeable on a boxed mattress for a mechanical reason rather than a chemical one: the foam has been compressed and vacuum-sealed in plastic for weeks, so everything that would have dispersed gradually in a warehouse is released at once when you open it.
The smell is usually described as chemical, plasticky or like a new car. It is not a sign the mattress is faulty, and it is not specific to cheap mattresses.
How long, by construction
| Type | Typical | Note |
|---|---|---|
| Boxed memory foam | 2 to 7 days | Strongest initially. Compression concentrates it. |
| Boxed hybrid | 1 to 3 days | Less foam, and springs move air through it |
| Traditional pocket sprung | Hours to 2 days | Frequently barely noticeable |
| Latex | Days | A distinct rubbery smell rather than a chemical one |
| Natural fillings | Minimal | May smell faintly of wool |
A smell still strong after two to four weeks is worth raising with the retailer, because that is outside normal behaviour.
What actually speeds it up
Airflow. The only thing that genuinely works. Open windows, and if you can, put a fan in the room aimed across the mattress rather than at it.
Unwrap it immediately on delivery. Every hour it stays in plastic is an hour it is not airing, and this is the most common avoidable delay.
Stand it on edge for the first few hours if you have space, so both faces are exposed.
Warmth helps a little, because it increases the rate of release, so a mattress airing in a warm ventilated room clears faster than in a cold closed one. Ventilation matters more than temperature.
Leave it unmade for the first day or two. Bedding over a new foam mattress traps what you are trying to release.
What does not help
Air fresheners and sprays. They add a smell rather than removing one, and on a new mattress you now have two.
Fabric softener or scented sprays on the mattress itself. They leave residue on a surface you cannot wash.
Bicarbonate of soda absorbs odour molecules from a surface and does very little about a gas being released from within foam. It is the right tool for a urine smell and the wrong one here.
Steam cleaning, which drives moisture into the fillings, can void the guarantee, and does nothing for off-gassing.
If you are sensitive to it
Most people find it unpleasant rather than a problem. Some people react more, particularly with asthma or chemical sensitivities.
Air it in a different room for two or three days before it goes in the bedroom, which is the simplest answer and is worth planning for at the point of ordering.
If you want to minimise it from the start, natural fillings and traditional sprung constructions off-gas far less than boxed foam, and latex smells of rubber rather than chemicals.
Look for a certification you can check rather than the word natural, which is unregulated in bedding. If you have a respiratory condition and are concerned, a GP or pharmacist is the right person to ask rather than a retailer.
While it airs, it is also expanding
A boxed mattress needs time to reach full height, and the two processes run together.
Most reach usable shape within a few hours and full height can take 24 to 72 hours, longer in a cold room because foam is stiffer when cold.
Do not judge the firmness for at least a fortnight. A new mattress feels different from the old one you have adapted to, and your body takes that long to recalibrate. This is also why sleep trials usually have a minimum period of around 21 to 30 nights before you can return.
And a mattress that has been compressed cannot be re-rolled once expanded, which matters if you were planning to move it in a box.
Preventing it, which happens before delivery
Once a mattress is unwrapped in your bedroom the smell is a fact and all you can do is ventilate. Every real lever is earlier than that, and there are three of them.
At the point of choosing. This is the only decision that removes the problem rather than shortening it. The table above is also a shopping list in reverse order: a traditional pocket sprung mattress with natural fillings is frequently barely noticeable, latex smells of rubber rather than chemicals, a boxed hybrid has less foam and more air passing through it, and boxed memory foam is the strongest of the lot. If there is somebody in the house with asthma, or you simply have nowhere to air a mattress for three days, that ranking is worth more than it looks.
At the point of ordering. Ask how long it has been in the box, because off-gassing starts when the foam is made rather than when you open it, and a mattress that has been boxed up for weeks has done part of the work already. Then time the delivery so that the mattress can be unwrapped on the day it arrives, in a room you are not about to sleep in. A boxed mattress that arrives on a Friday and gets opened on a Sunday has wasted the two days you had.
At the point of unwrapping. Cut the plastic off outside the bedroom if you can carry it, open the windows in whichever room it is going to stand in, and leave it on edge rather than flat so both faces are exposed. The plastic itself goes straight out of the house; it holds the smell strongly and it is the reason a room can still smell after the mattress has stopped.
One thing not to do early, which is the opposite of the advice given on nearly every other page on this site: do not fit the mattress protector until the airing is finished. A protector is a barrier to water vapour by design, and on a brand new foam mattress it is a barrier to everything else coming out of it too. Put it on once the smell has gone and keep it on from then until the day the mattress leaves the house. Why breathability is the specification to buy on is covered on the best mattress protectors.
Related reading
Setting up a new mattress
Lower-emission constructions
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Questions people ask
How long does new mattress smell last?
Two to seven days for boxed memory foam, one to three for a boxed hybrid, and often hours for a traditional sprung mattress. A smell still strong after two to four weeks is worth raising with the retailer.
What causes new mattress smell?
Off-gassing: polyurethane and viscoelastic foams release small amounts of volatile organic compounds as they cure and air. It is more noticeable on boxed mattresses because compression in plastic concentrates the release.
Is new mattress smell harmful?
Most people find it unpleasant rather than a problem, though some react more, particularly with asthma or chemical sensitivities. Airing it in another room for a few days before it goes in the bedroom is the simplest answer.
How do I get rid of new mattress smell faster?
Airflow is the only thing that genuinely works. Unwrap it immediately, open windows, aim a fan across it, stand it on edge if you can, and leave it unmade for a day or two.