The job of a thermal top is simple: keep you warm while moving moisture away from your skin.

When you’re active in cold conditions, managing sweat matters. If you stay dry, you stay warmer.

Thermals also make layering more effective. Get your next-to-skin base layer right first, and everything else works better on top.

Key features to look for:

• Moisture-wicking capability

• Insulation (how well it traps heat)

• Breathability (so you don’t overheat)

Get these right, and you’ll stay warm, dry, and comfortable in a wider range of conditions.

There’s a reason merino has become a go-to in the outdoors. It’s not the cheapest option, but it’s earned its place with natural performance across all seasons.

Merino wool thermals are built from fine wool fibres that manage temperature naturally. They keep heat in when it’s cold but don’t trap excess warmth when you’re moving.

One standout feature is moisture handling. Merino can absorb a decent amount of moisture without feeling wet, which helps keep your body temperature stable.

Merino is also naturally odour-resistant. Many hikers and hunters prefer merino for this reason. You can wear merino thermals multiple times without them getting unpleasant, which is useful on multi-day trips.

Comfort is another reason merino is a popular choice for the outdoors. Its fine fibres make it soft against the skin for all-day use, without the itch you get from traditional wool.

Key Benefits of Merino Wool Thermals

• Natural temperature regulation

• Odour resistance for extended wear

• Soft, comfortable feel

Even when damp, merino wool thermals still insulate well.

Drawbacks of Merino Wool Thermals

• Higher cost than synthetic options

• Require more careful washing

A drawback to some merino thermals is they tend to wear out faster than synthetic options. Bushbuck blends its merino clothing with Cordura® nylon to improve durability, so it holds up better over time.

Synthetic options, including polypro thermals, are also a great option for using while active. They’re typically made from polyester or polypropylene and excel at moving sweat away from your skin.

Where they really stand out is drying speed. If you’re working hard and build up a sweat, they’ll dry fast once you slow down or hang them out over your lunch break. Likewise, if you’re caught in the rain, they’ll dry out a lot quicker in the hut than wool ready for your next wear. 

Synthetics are also lighter and more durable than most merino thermals, which makes them easy to pack and tough enough for repeated use.

Key Benefits of Synthetic Thermals

• Fast drying

• Lightweight and packable

• Strong durability

That combination makes polypro thermals a solid choice for high-output activities.

Drawbacks of Synthetic Thermals

• Can hold onto odour over time

On multi-day trips, they can start to smell after sweating in them, which is why some people avoid synthetics.

Both options are built for the same job but they have different strengths.

Merino Wool Thermals:

• Natural temperature control

• Odour-resistant

• Natural material

Synthetic Thermals (including polypro thermals):

• Quick-drying and lightweight

• Durable and hard-wearing

• More budget-friendly

If you’re choosing a thermal, it comes down to budget and how you use it, steady wear versus high-output activity.

Warmth and Temperature Regulation

Merino wool thermals adapt to your body temperature. They keep you warm in the cold without overheating when you’re moving.

• Merino thermals: Regulate temperature naturally

• Synthetic: Provide insulation but are less adaptive

If you want steady comfort across changing conditions, merino is hard to beat.

Moisture Management and Drying Speed

Both handle moisture, just differently.

• Merino wool thermals: Absorb moisture but still feel dry

• Polypro thermals: Move moisture fast and dry quickly

For stop-start or all-day wear, merino works well. For intense output or wet conditions, synthetic has the edge.

Odour Resistance

• Merino thermals: Naturally resist odour

• Synthetic: Can retain smell over time

If you’re wearing your thermal top multiple days in a row, merino stays fresher for longer.

Durability and Care

• Merino wool thermals: Need gentler care

• Polypro thermals: Tough and easy to wash

If you want low-maintenance gear, synthetic is the simpler choice.

The right thermal top depends on where and how you’ll use it.

Key things to weigh up:

• Activity level (low vs high output)

• Conditions (cold, wet, variable)

• Budget

For Outdoor Enthusiasts and Athletes

If you’re moving hard, moisture control matters most.

• Polypro thermals: Best for fast drying and durability

• Merino wool thermals: Better for regulating temperature over long days

Both have a place. The choice depends on intensity and conditions.

For Parents and Kids Thermals

When choosing childrens thermal tops, comfort and practicality come first.

• Merino wool thermals: Soft, warm, and good for sensitive skin

• Polypro thermals: Affordable and durable

For growing families, having a mix of kids thermals often makes sense.

Our Top Picks

Bushbuck Combat Merino Thermals Bushbuck merino clothing is reinforced with Cordura® nylon, making it five times more durable than regular spun merino wool. Best suited for all-round use, with strong odour resistance and natural temperature regulation across changing conditions and seasons.

Bushbuck CoreTech Thermals The CoreTech thermal is Bushbuck’s take on a classic camping and adventure essential. Warm as, tough as, and built from 100% recycled polyester. A practical option for high-output use, with fast-drying performance.

Bushbuck Kids Clothing Built for real use, Bushbuck kids clothing is made to handle everything from school sports to outdoor adventures. With options including childrens thermal tops in both merino and polypro, it’s a practical choice for keeping kids warm, dry, and comfortable in all conditions.

There’s no single winner. It depends on use.

Merino wool thermals are the better all-rounder for comfort, warmth, and multi-day wear. Polypro thermals and other synthetics shine when you need durability and fast drying.

Blended options like Bushbuck Combat Merino are a great all-rounder, combining the natural performance of merino thermals with improved durability.

Pick your thermal based on how you actually use it, not just the label.

Why is merino the best type of wool?

Merino is considered the best because its fibres are finer and softer than standard wool. This gives merino wool thermals better comfort, temperature regulation, and moisture control.

What is the difference between wool and merino wool?

The key difference is fibre quality. Merino wool comes from merino sheep and is much finer, softer, and more breathable than regular wool. That’s why merino thermals feel comfortable against the skin, while standard wool can feel coarse and less suited for base layers.

Why is Merino wool so expensive compared to normal wool?

Merino wool costs more due to its finer fibres, specialised farming, and processing requirements. The performance benefits, like comfort, odour resistance, and temperature regulation, also add value. This is why merino wool thermals are priced higher than basic wool or synthetic options.

Which fabric has the best moisture wicking properties?

Synthetic fabrics, especially polypro thermals, typically have the best moisture-wicking performance. Merino moves sweat away from the skin quickly and dry fast. Merino thermals manage moisture differently by absorbing it while still feeling dry, which suits longer, lower-intensity use.

What is the best fabric to keep you warm in winter?

For consistent warmth, merino wool thermals are one of the best options. They trap heat effectively while still breathing, so you don’t overheat. Synthetic options also insulate well, but merino stands out for managing temperature control in changing conditions.

What are the best thermals for cold weather?

The best option depends on activity level. Merino wool thermals are ideal for steady wear, offering warmth and comfort over long periods. For high-output conditions, polypro thermals perform well due to their quick-drying properties. Many people use both depending on the situation.