A microfiber mattress topper is a quilted layer filled with very fine polyester fibers that sits on your mattress and makes it feel softer and plusher. It is the fluffy, down-like kind of topper, not the dense foam kind, so it adds cushion without the slow hug of memory foam.
So what is the fiber, what does GSM mean, will it sleep hot, can it be washed and why do some go flat? We make an 800 GSM fiber topper, so these are the questions we hear most. Here are straight answers. You can also browse every option in our mattress topper collection.
What is a microfiber mattress topper made of?
Microfiber is a synthetic fiber, usually polyester, spun thinner than a strand of silk. The regular polyester fiberfill inside cheap cushions uses thicker strands that feel springy and a little coarse. Microfiber is so fine that a handful feels closer to down: soft, light and quick to give under your palm.
In a microfiber mattress topper, that fill is sewn inside a fabric shell. On many toppers the word "microfiber" describes only the fill, and on some it describes the shell too, so read both lines of the label. The shell decides a lot about how the topper breathes and how it feels under a fitted sheet. On ours, the microfiber is the filling and the shell is a breathable white fabric.
The last piece is the stitching. Loose fill drifts. Box stitching sews the topper into a grid of square pockets, and each pocket holds its own share of fiber. If you have ever owned a cheap duvet that ended up with all the stuffing at the foot end, you already know why this matters.
Microfiber vs polyester and cotton fill
These three get mixed up a lot. Microfiber is a polyester fill, just a much finer one, so "microfiber vs polyester" is really fine fiber vs coarse fiber. The fine version feels softer and drapes more like down. The coarse version feels bouncier and lumpier.
Cotton batting is a different animal. It is heavier and firmer, and it packs into a dense, flat layer over time. It breathes well, but it feels more like a thin futon than a pillow top.
What does 800 GSM mean on a mattress topper?
GSM stands for grams per square metre. On a topper it describes fill weight: how many grams of fiber sit under each square metre of the surface. A higher number means more fiber in the same space, which usually means more loft and a slower slide toward flat.
We think it matters more than thickness. Two toppers can both measure 4 inches on day one, but the one with less fill usually loses that height faster, because fill weight is what holds the loft up.
Here is what 800 GSM works out to across the three sizes of our 4 inch microfiber topper. These are our own rough sums: surface area multiplied by 800 grams, for the fill only, not the shell.
| Size | Dimensions | Surface area | Approx. fill weight |
|---|---|---|---|
| Single | 78 x 42 in | about 2.1 square metres | about 1.7 kg |
| Queen | 78 x 66 in | about 3.3 square metres | about 2.7 kg |
| King | 78 x 84 in | about 4.2 square metres | about 3.4 kg |
Why bother with the maths? It shows what you lift every time you change the sheets, and whether your washing machine can cope.
Microfiber vs memory foam: which topper feels better?
Honestly, they solve different problems. Memory foam changes how the surface shapes around you. Microfiber changes how soft and cushy the surface feels.
Lie on memory foam and it feels firm for a moment, then it warms and slowly molds around your shoulder and hip. Lie on a lofty microfiber mattress topper and you sink in straight away, like dropping onto a thick duvet. Roll over and it springs back at once. Neither is better in general. It comes down to what bothers you about your bed.
| What you care about | Microfiber topper | Memory foam topper |
|---|---|---|
| First feel | Soft and fluffy, sinks in at once | Firm at first, then slowly molds |
| Cushioning | Gentle, even give across the surface | Deeper contouring at hips and shoulders |
| Turning over | Easy, springs back right away | Slower, can feel "stuck" |
| Heat | Air moves through the fill | Dense foam tends to hold heat |
| Cleaning | Whole topper, if the care label allows | Foam core is usually spot clean only |
| Handling | Light and easy to shake out | Heavy and floppy to move |
| Upkeep | Needs regular shaking and fluffing | No fluffing, but body prints can form |
| New smell | No foam off-gassing smell | Can smell of foam for a while |
A simple way to decide: if your mattress feels hard as a board under your hips and shoulders, foam does more to cushion those pressure points. If the support is fine and you just want the bed to feel softer and cosier, closer to a hotel bed, a fiber topper usually feels nicer. Weighing up height as well? Our guide on whether a 4 inch topper is too thick covers that part.
Does a microfiber topper sleep hot?
It is usually cooler than solid memory foam and a little warmer than a bare mattress with a cotton sheet. Fiber fill is a loose web with air between the strands, so warmth has somewhere to go. Foam is a dense block pressed against your body, and that close contact holds heat.
The Sleep Foundation's mattress topper testing notes list down alternative toppers among the materials with the best temperature control. The same notes say most foam toppers contour so closely that they restrict airflow. Microfiber is a down alternative fill, so it sits on the cooler side of that list.
Their notes make a second point that people often miss: the cover counts as much as the core. A breathable fill inside a fabric that blocks air can still feel warm. The same goes for what you pile on top. A microfiber mattress topper under a synthetic fitted sheet and a heavy duvet will feel warm however airy the fill is.
If you run hot, this is what we would change first:
- Put a crisp cotton percale fitted sheet over the topper.
- If you use a protector, choose a breathable one that does not crinkle.
- Swap a heavy winter duvet for a lighter blanket in summer.
Can you wash a microfiber mattress topper?
Often yes, but the care label on your topper has the final say. Some fiber toppers are made for a home machine, some need a large commercial washer and a few are spot clean only. Our product page keeps it simple: follow the care label for washing and drying, and make sure the topper is completely dry before it goes back on the mattress.
That last step is where people slip up. A thick fiber topper can feel dry on the outside while the centre of each pocket is still damp. Put a sheet over it like that and you get a musty smell, and the fill clumps as it dries.
Before you wash, glance back at the fill weights in the GSM table. A king holds roughly 3.4 kg of fiber before you count the shell, and water makes it far heavier. Cram that into a small drum and it cannot rinse or spin properly. If the label allows machine washing and your machine is small, a laundromat's large washer and dryer is the easier route.
When the label allows tumble drying:
- Use the heat setting the label gives, never hotter.
- Add two or three dryer balls to break up clumps as it turns.
- Stop every so often, pull the topper out, shake it hard and carry on.
- Squeeze the thickest corners. If you feel any coolness, it is not done.
You can also wash it far less. A protector on top catches sweat and spills and is much easier to launder. Our post on using a topper and a protector together explains how to layer them.
Why fiber toppers go flat, and how to bring the loft back
Every fiber topper compresses with use. Your body presses the same spots night after night, the strands pack together and the loft drops where you lie. This happens with any loose fill, down included, and it is the main trade-off against foam.
What slows it down is fill weight, stitching and a little routine. This is the one that works for us:
- Every week or two, when you change the sheets, lift the topper and give it a few firm shakes, the way you shake out a duvet.
- Pat each box pocket to push the fiber back out to its edges.
- Every month or so, turn it head to foot so your hips land on a fresher section.
- On a dry day, air it out by an open window for an hour or two.
If your new microfiber mattress topper arrives folded tight in its packaging, shake it out, lay it flat and give it several hours before you judge the loft. Once it has puffed up, hook the elastic corner straps under the mattress and it stays put.
So when does flat mean finished? If the topper stays thin and lumpy even after a good fluff and a wash, the fiber has matted for good and it is time to replace it. If the topper looks fine but you still feel a dip, check the mattress. A topper follows the shape beneath it. It cannot fill a sag.
Who should choose a microfiber mattress topper?
These are the cases where a microfiber mattress topper tends to be the right buy:
- Your mattress is supportive but feels too firm or a bit tired on top.
- You want a plush, sink-in hotel feel rather than the slow hug of foam.
- You turn over a lot and hate feeling stuck in one spot.
- You want to clean the whole topper, not just a removable cover.
- You would rather avoid down and feathers.
- You are setting up a guest bed and want it comfortable without buying a new mattress.
And when to pick something else: if your mattress sags in the middle, if you sleep on your stomach and like a firm, flat surface, or if you want deep contouring at the shoulder and hip, foam or a new mattress may suit you better.
If a fiber topper sounds right, our plush 800 GSM microfiber mattress topper gives you 4 inches of loft, box stitching and elastic corner straps, in Single, Queen and King. The fill is completely down-free. It sits alongside the rest of our hotel-quality pillows and bedding, and it comes with 30-day easy returns: if it is not right, you can return an eligible item within 30 days of delivery.
Frequently Asked Questions
Is a microfiber mattress topper good?
Yes, if you want a softer, plusher surface on a mattress that still supports you well. It gives a fluffy, hotel-style feel and is light to handle. It will not give the deep contouring of memory foam or fix a sagging mattress.
Is microfiber or memory foam better for a topper?
Neither wins for everyone. Memory foam molds closely around hips and shoulders and suits people who want that hug. Microfiber feels lighter and fluffier, lets you turn over easily and tends to sleep cooler than solid foam.
Are microfiber toppers hot to sleep on?
They usually feel cooler than solid memory foam because air moves through the fill. Your sheets and duvet still matter a lot, so pair the topper with breathable cotton sheets if you run warm.
Can you put a microfiber topper in the washing machine?
Check the care label first, since it sets the rules for washing and drying. If machine washing is allowed, use a machine big enough for the fill to move, and dry the topper completely before you put it back on the bed.
What does GSM mean on a mattress topper?
GSM means grams per square metre, and on a topper it tells you how much fill sits under each square metre. A higher GSM usually means more loft and better resistance to going flat.
Is microfiber the same as down alternative?
Microfiber is one of the most common down alternative fills. It is a very fine polyester fiber made to feel soft and lofty like down, without using any feathers or down clusters.
Why does my fiber topper go flat?
Your weight presses the fibers together in the same places every night. Shaking and patting the topper every week or two, and turning it head to foot now and then, spreads the fill back out and keeps the loft even.
Will a microfiber topper slide off the mattress?
A topper with elastic corner straps should stay in place, because the straps hook under the mattress corners. A fitted sheet pulled over the top holds it steady too.
