Last Updated on October 4, 2026 by Umar Farooq
The honest answer to how to wash a mattress topper is that most of them cannot be washed, and the ones sold in the largest numbers — memory foam — must never go in a washing machine at all. Tempur-Pedic puts it in capitals on its own care page: “Do NOT wash or Dry Clean the TEMPUR-Topper Supreme.” Sleep Number’s instruction for the foam inside its mattress layers is three words long: “Foam: Spot clean only.”
So before anything else, work out which of three things you own. A removable cover over a foam or latex slab, a solid foam slab with no cover, or a fibre-filled pad. Only one of those three goes through a cycle, and even that one has conditions.
Look for a zip before you look for a cycle
Start at the corners and run your hand along the long edge. Most quality toppers have a zip running two or three sides, and if yours does, you have just found the only washable part of it. Tempur-Pedic confirms the general case: “The covers on most of our mattress toppers can be removed and washed,” and adds the sensible caveat that if you cannot tell, “please refer to the tags sewn into the cover or contact our Customer Service department” (product care).
This changes the whole job. The cover is a straightforward textile — big, awkward, but ordinary — and the cover is also what has been in contact with the sheet, the sweat and whatever was spilled. The slab underneath is usually far cleaner than people assume, because something has been between it and the bed for its entire life.
If there is no zip, you own a sealed topper. That is a spot-clean item, permanently, and the sections below on cleaning and drying are the whole available procedure.
Memory foam: the makers say no, and they are not hedging
Two separate things go wrong, and both are mechanical rather than chemical.
Foam is an open-cell structure, which means it is mostly air held in a web of thin polyurethane walls. Saturated, it holds several times its dry weight in water, and that weight is carried entirely by those walls. Add the tumbling and the acceleration of a spin cycle and the walls tear internally — not visibly, but the topper afterwards has soft dead patches that never recover their support. Whirlpool says the same thing about foam pillows, which fail in exactly the same way: “To keep the foam from breaking apart, memory foam pillows should never be washed in a washing machine” (how to wash pillows).
The second problem is that a soaked foam slab cannot be dried. Water sits in the middle of a three-inch block of closed, slow-draining material with no airflow through it, and a dryer cannot reach it without heat that would damage the foam first. What you get is a topper that feels dry on both faces and is still wet in the core a week later, which is a mould problem rather than a laundry one.
Latex behaves no better. It is denser than memory foam, so it holds even more water and dries even slower, and strong detergent degrades the rubber. Sleep Number’s instruction for its own foam layers covers both materials: “Spot clean foam with warm soapy solution and mild detergent. Do not saturate” (cleaning your mattress pad or layer). Do not saturate is the operative instruction, and it is the one most home remedies ignore.
Fibre and feather toppers are the exception, with conditions
A fibre-filled or down topper — often sold as a mattress pad rather than a topper — is a different object. It is a quilted shell with loose fill, so it behaves like a thin duvet, and a thin duvet is washable. Sleep Number’s care line for its Total Protection Mattress Pad reads: “Machine wash warm with cold rinse. Wash separately in large capacity front loading washer and dryer. Use mild detergent, delicate cycle,” followed by “Tumble dry on low heat turning frequently to avoid scorching.”
Three conditions are buried in that. Separately, large capacity, and front loading. A king fibre topper soaked through is one of the heaviest single items you will ever ask a drum to spin, and a top-loader with an agitator is the worst place to find that out. If your machine is small, this is the same decision as the one on the weighted blanket page: the laundrette, or nothing.
How to wash a mattress topper cover without shrinking it
Assuming the zip exists, this part is easy and the only real risk is heat shrinking the cover so it no longer goes back over the slab.
- Unzip it fully and get the foam out flat. Lay the slab on a clean sheet somewhere it can air while the cover is away.
- Cold water, gentle cycle, mild detergent. Tempur-Pedic: “We recommend a cold temperature setting for machine washing and a cool setting for machine drying.” Sleep Number says the same for its outer covers — gentle, cold, “do not bleach.”
- Wash it on its own. A topper cover is a very large flat piece, and it will collect anything smaller inside itself.
- Cool dryer, or line dry, and take it out early. Sleep Number’s wording is “Tumble dry low. Remove promptly. Do not iron.” A cover that has shrunk by three per cent will not zip back round the foam, and there is no fixing that.
- Put it back on only when the slab is completely dry. Zipping a dry cover over a slightly damp slab seals the moisture in, and the smell arrives about four days later.
Cleaning the slab you cannot put in a machine
This is the actual procedure for the majority of toppers, and it is more effective than it sounds — most of what makes a topper unpleasant is on or just below the surface.
- Vacuum both faces with an upholstery head, slowly, working in overlapping passes. Dry debris lifts out easily and will not if you wet it first.
- Deodorise with bicarbonate of soda. A thin even layer, left for several hours, then vacuumed off completely. It is not a cleaning agent; it absorbs odour compounds and moisture, which is a different and useful job.
- Spot clean with a barely damp cloth. Blot, do not rub, and work from the outside of a mark inwards. Rubbing drives the stain down into the foam where you cannot reach it.
- Protein stains need an enzyme cleaner, applied to the cloth rather than to the foam. Sweat, blood and urine are not dirt — they are material that has to be broken down rather than lifted.
- Never soak, and never pressure wash. Both put water where the next section says you cannot get it out from.
Drying is where a soaked topper is actually lost
If a topper has already been soaked — by a spill, by a flood, or because somebody put it in a bath — the clock matters more than the technique. Foam that stays wet for more than about forty-eight hours in a warm room is a mould risk, and mould in the interior of a foam slab cannot be removed.
Press, do not wring. Lay the topper flat and press down with dry towels across the whole surface, replacing the towels as they load up. Then stand it on its long edge in moving air, with a fan pointed at one face, and turn it every few hours. Sunlight helps and also degrades foam, so an hour outdoors is useful and a day is not. Direct heat — a radiator, a hairdryer, a heater aimed at it — will cook the surface closed and trap the water behind it.
If it still feels cool or heavy in the middle after two days, it is not going to recover, and sleeping on it is not the right call.
FAQ
Can you put a mattress topper in the washing machine?
Only if it is fibre-filled, and then only in a large-capacity front loader on its own. Memory foam and latex never go in a machine — Tempur-Pedic says “Do NOT wash or Dry Clean” its topper, and Sleep Number’s instruction for foam is “spot clean only.”
How do you clean a memory foam mattress topper?
Vacuum both faces, deodorise with bicarbonate of soda left for several hours and then vacuumed off, and spot clean marks with a barely damp cloth and a mild detergent or enzyme cleaner. Sleep Number’s limit is the one to hold to: “Do not saturate.”
Can a mattress topper go in the dryer?
A fibre pad can, on low heat, turned frequently — Sleep Number warns about scorching. A foam or latex slab cannot, at any setting. A removable cover can on cool, and should come out before it is fully dry so it does not shrink away from the foam.
How often should a mattress topper be cleaned?
Vacuum and deodorise every three to six months, wash the cover when you wash the rest of the bedding, and deal with spills the day they happen. The cover is doing nearly all the work, which is why it is the part that needs a schedule.
Will a mattress topper shrink if washed?
The cover will, which is the practical problem — a shrunken cover will not zip back over the slab. Cold water and cool drying prevents it. The foam itself does not shrink; it tears.
Is a mattress topper the same as a mattress protector?
No, and they fail in opposite ways. A topper is a comfort layer, usually foam, usually not washable. A protector is a thin waterproof barrier that is washable but destroyed by heat — how to wash a mattress protector covers that one.
Protect it, because you cannot launder it
The useful conclusion here is a purchasing one rather than a laundry one. A foam topper is a sealed comfort layer with a service life, and nothing you do with water will extend it. What extends it is never needing to clean it: a washable protector over the top, a fitted sheet over that, and the spills dealt with before they reach the third layer down.
That is an unsatisfying answer for anyone who arrived here with a stain and a bathtub in mind, and it is the true one. Vacuum it, deodorise it, blot what you can, and put something washable between it and the bed. It is the same logic that keeps a pillow to two washes a year rather than none — and pillows, at least, can go in the machine.
