Wool Mattress Topper & Underlay: The Warm, Natural Way to Upgrade Your Bed
Bedding & Winter Guide
Wool Mattress Topper & Underlay: The Warm, Natural Way to Upgrade Your Bed
A wool underlay adds cosy warmth in winter, breathable comfort in summer and a plush new feel to a tired mattress. Here's how to choose the right one — GSM, sizes and care.
A wool mattress topper (also called a wool underlay or underblanket) is one of the best-value upgrades you can make to your bed. Laid on top of your mattress and under your sheet, it adds a plush layer of cushioning while wool's natural fibres do something synthetic toppers can't: regulate your temperature — trapping warmth on cold winter nights, yet breathing and wicking moisture so you don't overheat in summer.
In this guide we cover why wool works so well, how to read GSM ratings, what size to buy, and how to care for a wool underlay so it lasts for years.
Quick answer: A wool mattress topper adds warmth, comfort and temperature regulation to any bed. For year-round use in most Australian homes, a 500–550GSM wool underlay is the sweet spot — warm enough for winter, breathable enough for summer. Choose a size that matches your mattress and check it has secure elastic corner straps.
Why Choose a Wool Underlay?
Wool is a natural temperature regulator. Its crimped fibres trap pockets of warm air in winter, while also absorbing and releasing moisture as your body heat changes through the night — so you stay warm without the clammy overheating that synthetic toppers can cause. That makes a wool underlay ideal for couples who sleep at different temperatures, hot sleepers who still feel the winter chill, and anywhere with big day-to-night temperature swings (most of Australia). Wool is also naturally breathable and resistant to dust mites, a genuine plus for allergy sufferers.
What a wool topper does for your sleep
- Warmth in winter without needing to crank the heater
- Breathable in summer — wicks moisture and releases heat
- Extra cushioning that revives a firm or ageing mattress
- Naturally dust-mite resistant — good for allergies
- Long-lasting — quality wool holds up for years
Understanding GSM: How Warm Is Warm Enough?
GSM (grams per square metre) tells you how much wool pile the underlay has — the higher the number, the warmer and more cushioned it feels:
300–400 GSM
Lighter cushioning and warmth — suits warmer climates or those who don't want much added heat.
500–550 GSM
The all-rounder. Genuinely warm for winter yet still breathable for summer — the best single choice for most Australian bedrooms.
600GSM and above
Maximum warmth and plushness — ideal for cold climates, unheated rooms, or anyone who loves a really cosy bed.
SAVE 38% Australian Made
Recommended
Australian Wool Reversible Underlay — 550GSM
This is our pick for most beds: a genuinely Australian Made wool underlay with a generous 550GSM wool pile that hits the perfect balance of winter warmth and summer breathability. It's reversible, fits mattresses from Single to King with secure elastic corner straps, and instantly adds a plush, hotel-feel layer to a tired mattress. Backed by real Australian wool quality, not synthetic filler.
- 550GSM wool pile — warm in winter, breathable in summer
- Genuinely Australian Made
- Reversible for year-round use
- Sizes Single to King with elastic corner straps
- Naturally temperature-regulating & dust-mite resistant
What Size Wool Topper Do I Need?
Match the topper to your mattress size — Single, King Single, Double, Queen or King. A good wool underlay uses elastic corner straps to hold firmly in place under your fitted sheet, so it won't shift overnight. If you're between sizes or have a deep mattress, size up for a secure fit.
Wool vs Bamboo vs Memory Foam Toppers
Wool is the best natural temperature regulator — warm yet breathable, and naturally allergy-friendly. Bamboo charcoal toppers (like our 1000GSM Bamboo Charcoal Pillowtop) offer a soft, cushioned pillowtop feel with odour control, great for adding plushness. Memory foam gives the most pressure relief and contouring but sleeps warmer and less breathably than wool. For all-round natural comfort and Australian conditions, wool is the standout; for maximum cushioning, a pillowtop is worth a look.
How to Care for a Wool Underlay
Wool is wonderfully low-maintenance. Air it outside in the shade a few times a season — wool naturally self-freshens and resists odour. Spot-clean spills promptly, and follow the care label for washing (many wool underlays prefer gentle cold wash or professional cleaning). Never tumble dry on high heat, and store it breathable (a cotton bag, not plastic) when not in use. Treated well, a quality wool underlay lasts many years.
Common Questions
Wool Mattress Topper FAQs
Is a wool mattress topper good for winter?
Yes — wool traps warm air and holds body heat beautifully, making a 500GSM+ underlay a cosy winter upgrade. Because wool also breathes, the same topper stays comfortable into the warmer months.
Will a wool topper make me too hot in summer?
No — unlike synthetic or memory foam toppers, wool wicks moisture and releases excess heat, so it regulates temperature rather than trapping it. That's why wool suits year-round use in Australia.
What GSM wool underlay should I buy?
500–550GSM is the best all-rounder for most Australian homes. Go higher (600GSM+) for cold climates or unheated rooms, or lighter (300–400GSM) for warmer regions.
How do I stop a wool topper sliding around?
Choose one with elastic corner straps that loop over the mattress corners, then put your fitted sheet over the top. This holds it firmly in place all night.
Can you wash a wool mattress underlay?
Always follow the care label. Many wool underlays prefer a gentle cold wash or professional cleaning, and should be dried flat or line-dried away from direct heat. Airing outside regularly keeps it fresh between washes.
Is a wool topper good for allergies?
Wool is naturally resistant to dust mites and mould, which makes a wool underlay a good choice for many allergy sufferers compared with some synthetic fills.
Read next: Wool Doona Buying Guide · Winter Warmers
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