Smartwool Classic Thermal Merino Base Layer 1/4 Zip Review 2024

It’s a classic for a reason, the do everything, go anywhere base layer is the perfect base layer for all your adventures.

PROS

• 100% Merino Wool is odour-free, warm and feels great.
• Nice fitting, not too tight
• Looks great both on and off the crag.

It’s been a long time since we featured any Smartwool product on the site – we don’t know why. Maybe we get busy adventuring and forget. So we’re addressing that by featuring a couple of classic items this season. 

First off is the Classic Thermal Merino Base Layer 1/4 Zip – this could be a very short review where I say there is absolutely nothing wrong and everything right with this base layer so just go ahead and buy one. But we’re gear freaks and you deserve a good dive into why it is such a great base layer.

Made using 100% Merino Wool which is ZQ Certified (the gold standard for sustainable Merino wool) the Thermal Merino Base Layer is super warm and soft when worn next to your skin. I occasionally feel a little itchy in wool but I haven’t had any problems with this top. The tight interlock knit offers a cotton-like feel and the flatlock seams mean no chaffing when on the move. The knit is standard throughout so isn’t like the Intraknit which means you can wear it for normal casual wear with a gilet or office jacket. The thermal top is a heavier weight knit so if you want something lighter the All Season top would be a good choice for you.

Warm enough to wear on it’s own on milder days – end of the day brew.

I’ve been using it all season for just about everything, working from home, cycle commuting to work, the gym and climbing wall; hiking both locally and in the mountains as well as running. It has performed well in everything. The fit is slim fitting but not what I would call a performance (race) fit. I’ve been using a size Medium and I have a standard size 40” chest and it has fit perfectly fine, not too tight that it restricts but not so baggy that it rucks and wrinkles under a shell. I’ve been using it mostly in conjunction with my Rab Vapour Rise Summit which has been just about perfect for the mild winter we’ve been having here in the UK. On milder days I’ve worn it with the Hudson Trail Vest which has proved a very breathable combination.

Great for hiking in – shown here with the Hudson Trail Vest.

Ventilation is provided by the deep 10” zipper which has worked well, I like the contrast colour way that compliments the colour of the top (I’ve been using the Honey/Charcoal one), which is a nice detail. The neck isn’t too tight either, I’m a 16.5 collar size in shirts and I’m able to zip the collar up when the breeze picks up. The collar has been staying upright with the zip done 3/4 of the way up.

The collar worked well zipped up and kept the warmth in – shown here under my Rab Vapour Rise.

I’ve been using it fairly regularly for a couple of months now and haven’t washed it yet (note to self best do that soon) it still doesn’t smell so I keep using it. Finishing touches include an elasticated collar taping, bar-tacked hook tab and a discreet ‘Funny Man’ logo.

The Smartwool Classic Thermal Merino Base Layer 1/4 Zip comes in an amazing 8 colour options and sizes S – XL. There is also a women’s version that also comes in 8 colour options and sizes XS-XL.

The SRP is £109.99 and it can be purchased directly from Smatwool UK and specialist retailers.

Disclosure – CGR reviewers and writers are never paid to provide a review and the website does not take advertising or link to affiliate sales. We are a bunch of keen climbers and travellers who accept sample products and offer an honest and independent review of the item.