by Quick answer: Air out a new mattress for at least 24 to 72 hours in a well-ventilated room before sleeping on it. Mild smells often clear in a day; stronger off-gassing from dense memory foam can linger up to a week. Open windows, run a fan, and keep the mattress uncovered.
By the MattressNut editorial team — Updated June 2026
What Off-Gassing Is (and Whether It’s Dangerous)
New foam mattresses release volatile organic compounds (VOCs) as the compressed foam expands. That chemical “new mattress” smell is off-gassing. It’s most pronounced with bed-in-a-box models that have been vacuum-sealed and rolled for weeks before delivery, and it’s strongest in the first few hours after unboxing.
For most people, the smell is an annoyance, not a health threat. Look for CertiPUR-US or GREENGUARD Gold certification on the label—these programs test and cap emissions, so certified foams off-gas at much lower levels than uncertified ones. If you or someone in your household is chemically sensitive, asthmatic, or pregnant, air the mattress out longer and consider sleeping elsewhere for the first night or two.
Want to speed up the process once it’s aired out? See our guide on how to get rid of mattress smell for a full playbook.
How Long by Mattress Type
| Mattress type | Typical off-gassing window |
|---|---|
| All-memory-foam / bed-in-a-box | 48–72 hours; up to a week for dense foam or strong smells |
| Poly-foam hybrid (coils + foam comfort layer) | 24–48 hours; less foam means less off-gassing |
| Innerspring (minimal foam) | A few hours to one day |
| Natural latex | Mild rubbery smell, 1–3 days; no synthetic VOCs |
| White-glove delivered (e.g., Saatva Classic) | Little to no off-gassing—arrives fully expanded, not compressed |
The thicker the all-foam core, the longer the wait. A 12-inch memory-foam mattress simply holds more compressed material than a 10-inch hybrid with a single foam comfort layer.
How to Speed Up Airing Out (and Expansion)
Unbox the mattress the moment it arrives—every hour it stays sealed is more time the VOCs spend concentrated inside the packaging. Once out:
- Open windows and run a fan pointed at the mattress surface. Moving air carries odor molecules away; a closed room just recirculates them.
- Raise room temperature slightly. Warmth accelerates off-gassing, which sounds counterintuitive, but getting it done faster in a day beats a slow drip over three days.
- Baking soda. Sprinkle a light coat over the bare mattress, leave it two to four hours, then vacuum thoroughly. It absorbs residual odor rather than masking it.
- Keep sheets off. Covering the mattress traps VOCs and slows expansion. Wait until the smell is largely gone before putting on a mattress protector or sheets.
On expansion: Bed-in-a-box mattresses also need 24 to 72 hours to reach full height after unboxing. Most reach 90% of their final shape within a few hours, but sleeping on an under-expanded mattress can feel firmer than expected and may slow the process. If the mattress seems thinner than advertised after 72 hours, contact the manufacturer before assuming it’s defective.
Our Pick If You Want to Skip the Wait
If off-gassing is a concern—whether for health reasons or just because you need the bed ready tonight—a mattress that arrives fully set up sidesteps the problem entirely. The Saatva Classic ships via white-glove delivery: two people bring it into your room, set it up, and haul away your old bed. No boxed compression, no chemical bloom, no 48-hour wait.
See the Saatva Classic and its 365-night trial →
Read our full Saatva mattress review for more on materials and feel.
Frequently Asked Questions
Is it safe to sleep on a new mattress right away?
Technically yes for most adults—the VOC levels from certified foam are low. But if the smell is strong enough to bother you while lying on it, that’s a good reason to wait. Sensitive individuals, young children, and pregnant women should air out longer and ventilate the room before the first night.
My mattress still smells after a week. Is something wrong?
A faint smell after a week is unusual but not unheard of with dense all-foam beds. Keep ventilating and try the baking-soda treatment. A strong, persistent chemical smell beyond ten days is worth reporting to the manufacturer—some will offer a replacement or a return under trial policies.
Does off-gassing stop completely?
Yes. VOC release tapers off exponentially—the first 24 hours account for most of it. After a week or two of normal use with regular airflow, off-gassing is effectively finished. You won’t notice a smell once it’s had time to air.
Does a mattress protector trap the smell?
It can, especially waterproof protectors with an impermeable barrier. Put the protector on after the mattress has aired out, not before. Using it during off-gassing can slow the process and cause the smell to concentrate between the protector and the mattress surface.
How do I know when the mattress has fully expanded?
Measure the height against the spec listed on the manufacturer’s site. Most foam beds reach full height within 24 hours; some thick all-foam models take closer to 72 hours. If it still seems low after three days, that’s when to call customer service.
Do latex mattresses off-gas the same way?
Natural latex has a mild, rubbery smell that clears within a couple of days. It doesn’t contain the synthetic VOCs associated with polyurethane foam, so the off-gassing window is shorter and the compounds involved are different. Synthetic or blended latex falls somewhere in between.
Bottom line: Plan on 24 to 72 hours of airing out in a ventilated room. All-foam beds take longest; innersprings and white-glove-delivered mattresses need little to no wait. Open windows, run a fan, skip the sheets until the smell clears.