A microfibre mattress topper is a quilted pad filled with very fine polyester filaments, and its job is padding rather than support. It makes a hard or tired mattress feel softer and deeper, it goes in the washing machine whole, and it runs cooler than a thick slab of foam. What it will not do is change how your weight is carried, so if your complaint is a specific ache at the hip or shoulder, read the comparison further down before you buy.
The word is doing less work than most listings imply. Here is what it means, what to look for on a label that often says very little, and how these toppers wear out.
What is a microfibre mattress topper?
In textiles, microfibre has a real technical meaning: a filament finer than one decitex, roughly a tenth the thickness of a human hair, with anything under 0.3 decitex called supermicrofibre. The fineness is the point, because thousands of thin filaments pack into something soft and dense, with a drape closer to down than to ordinary polyester wadding.
In bedding, nobody is checking. No UK labelling rule stops a manufacturer printing microfibre on a bag of coarse polyester fill, and the same word covers the shell fabric as well as the filling, which is why two toppers described identically can feel nothing alike. Judge these by construction, not adjective: a quilted shell holding a blown fibre fill in stitched boxes, plus some means of staying on the bed. Our Mattress Topper 10cm Extra Thick, Hotel Quality is that build: microfibre fill, cotton-blend cover, box stitching, deep elastic corner straps.
Is microfibre the same as hollowfibre?
No, and the difference is one you can feel. Hollowfibre is a coarser polyester staple with a hollow core, so air sits inside each strand and it builds springy height quickly for its weight. Microfibre is far finer and solid, so the same depth is denser and softer, with the draping feel people call silky.
Hollowfibre buys loft cheaply but coarsens and clumps with age. Microfibre settles more evenly but compresses more readily, so a thin one can feel like nothing. They fail differently, which matters more than which is better.
Is a microfibre mattress topper any good?
For one specific job, yes, and it is the best-value answer to it. If your mattress still supports you but feels thin, hard or unwelcoming, a deep fibre fill puts a real cushion between you and it, at far less cost per centimetre than foam.
Two honest limits. It cannot rescue a mattress that has lost its support: if yours dips more than about 3cm when you press down, you need a mattress. And it does not contour, so if pressure points rather than plushness are the problem, our Memory Foam vs Microfibre Mattress Topper: Which Should You Buy? is the head-to-head, and our Memory Foam Mattress Topper 4cm with Cooling Bamboo Cover is the other side of that choice.
A topper changes the surface you lie on, and that is the whole of its job. It is not a treatment for back pain, and ongoing pain is a conversation for your GP or a physiotherapist. Older pages on this blog are more enthusiastic than that. This is the accurate version.
Does a microfibre mattress topper sleep hot?
Cooler than solid foam, warmer than nothing. A passive topper has three levers: heat conducted away, air moving through it, moisture allowed to evaporate. Nothing unpowered removes heat from a bed, whatever the product name suggests.
Fibre does reasonably well on two of those three. An open fill held in stitched boxes has air paths through it, and a cotton-blend face carries sweat away rather than holding it against your skin. A solid foam slab has neither: it insulates, and damp warm air has nowhere to go. That is the structural reason fibre tends to feel cooler, whatever the marketing says.
Where fibre loses is sheer mass. Ten centimetres of anything is ten centimetres of insulation, so a very deep fibre topper in a warm room still feels warmer than a shallow one. The rule reverses the usual advice: for comfort deeper is better, for heat deeper is worse. Want height and a cool surface? Take the height from fibre and keep any solid foam shallow. Our Cooling Mattress Topper: What Actually Works (UK Guide) has the physics in full.
Heat exposure during sleep does measurably increase wakefulness and reduce deep and REM sleep, and humidity worsens it by blocking evaporation (Okamoto-Mizuno and Mizuno, Journal of Physiological Anthropology, 2012). A cooler, drier bed surface is a reasonable comfort goal. It is not a treatment for night sweats, menopausal flushing or heavy sweating, and if that is what keeps you awake, a pharmacist or GP is the right call.
What GSM should a microfibre mattress topper be?
GSM is grams per square metre, and for a fibre fill it is the closest thing to a real spec, because it says how much filling is in there rather than how tall the bag looks. Our What Is GSM in Mattress Topper? sets out the ranges.
The microfibre-specific point: because the filaments are fine and compress easily, a given GSM buys you less standing height than the same weight of hollowfibre, and more density. A low-GSM microfibre topper that looks plump in the bag will flatten under your hips within weeks. Between two toppers of the same advertised depth, the heavier one is almost always the one that lasts.
The awkward truth is that most listings do not state GSM at all. When it is missing, judge what you can see. Stitching should divide the surface into boxes or channels rather than leaving one open bag, because loose fill drifts to the edges and leaves you in a trough. Fixings should be a fitted skirt or deep elastic straps, not thin tapes. And a very low price on a very deep topper tells you something: that depth comes from somewhere, and if it is not fill weight, it is air.
How thick should it be?
Thickness advice online contradicts itself constantly because foam and fibre are measured on different scales. For memory foam, around 4cm is the working depth for most people. Fibre needs more loft before the bed feels different, and 7cm to 10cm is where a microfibre topper genuinely changes things. Below about 5cm you are buying a thick mattress protector with ambitions.
So a 10cm fibre topper and a 10cm foam topper are not comparable products, and any chart ranking them side by side on depth alone is misleading you. What is the Thickest Mattress Topper? covers the extremes.
Measure before you commit. A deep fibre topper adds real height, and the first sign of getting it wrong is a fitted sheet that will not hold the corners. Measure the mattress, add the topper depth, and buy a sheet deep enough to tuck underneath. Figures quoted elsewhere on this blog vary, so trust your tape measure.
Can you wash a microfibre mattress topper?
Yes, and this is the strongest practical argument for fibre over foam. A microfibre topper goes in whole, on a warm or cool wash. Ours is machine washable and safe to tumble dry, and the fill recovers its height afterwards.
Drying is where this blog has been inconsistent, so the rule plainly: fibre and microfibre fills can be tumble dried on low, and a couple of dryer balls help break up clumps. Memory foam must never go in a dryer or a washing machine at all. Waterproof protectors take low heat only. Dry a fibre topper right through before it goes back on the bed, because a fill still damp in the middle is how you get a musty smell. The Mattress Topper Cleaning Guide covers technique.
This is worth more than convenience. Laundering is mostly mechanical rather than thermal: in controlled testing, water or detergent alone removed roughly 84% of the dust mite allergen Der f 1 and 60 to 83% of live mites, at warm and cold temperatures alike, rising to about 98% with detergent plus bleach (Arlian, Vyszenski-Moher and Morgan, Journal of Allergy and Clinical Immunology, 2003, volume 111, pages 1269 to 1273). A topper you can put in the machine stays measurably cleaner than one you can only spot clean.
Is microfibre hypoallergenic?
The word is on almost every listing and means very little. Dust mites need warmth, humidity and shed skin, none of which belongs to a particular fibre type. The true version is narrower: a synthetic fill carries no feather or down protein, and it is launderable, which keeps the allergen load down.
Be careful what you expect from that. A Cochrane review of randomised trials of mite-reduction measures found no clear benefit for allergy symptoms or medication use, and concluded they cannot be recommended as a treatment. Cleaner bedding is worth having on its own terms and nothing more. If the real worry is spills or a barrier between body and bed, that is a protector's job, and our Waterproof Mattress Protector: UK Buyer's and Care Guide sets out what the evidence supports.
How long does a microfibre mattress topper last?
Less than foam, latex or wool, and there is no point pretending otherwise. Fibre is the shortest-lived of the common topper fills, and what fails is loft: the filaments compress and tangle under load, and shallow dips appear where your hips and shoulders sit.
Two things decide whether that means a couple of years or considerably more. First, fill weight, which is the GSM point above. Second, whether you wash it, because unlike foam, fibre partly recovers: a wash and a low tumble puts a fair amount of loft back, and a topper given that every few months ages far more slowly than one that never leaves the bed. Once high-density foam stops springing back, nothing restores it.
Storage is the other quiet killer. Long-term compression crushes loft, so do not keep a spare vacuum packed for months. Roll it loosely in a breathable bag. That goes double for foam, which long-term vacuum packing damages outright, whatever other pages here suggest.
Before you buy
- Padding or support? Padding points to microfibre. Pressure points on a hard mattress point to foam.
- How much fill, not how much depth? Check GSM if given. If not, judge the stitching and distrust a cheap deep topper.
- Will it stay put? Deep elastic corner straps or a fitted skirt. If yours already slides, How to Stop a Mattress Topper from Sliding is the fix.
- Will your sheets still fit? Measure the mattress, add the topper, buy accordingly.
Our microfibre and memory foam toppers, and the protectors that go over whichever you choose, are in Mattress Protector & Toppers.