We stand behind everything we make. We promise to make our products with incredible attention to comfort, fit, and durability—because we want you to love our gear as much as we do.
And we want it to be able to support all of your adventures, from exploring new cities to summiting new mountains. So if, for any reason, you aren’t completely happy with your Smartwool® gear within two years of purchasing, we’ll get you into some new gear. No problem.
Help keep your ski boots, hiking boots, and running shoes free of bulk and friction with our Men's Classic Thermal Merino Base...
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Temp Rating:
Classic Thermal
Warm
50° +
Cool
25° - 50°
Cold
<25°
Base Layer
Classic Thermal Merino
Made with 100% Merino wool for natural sweat management, odor-resistance, and temperature regulation.
Compare Base Layer Styles
Smartwool Base Layers
Responsibly sourced, naturally performing Merino wool—helping you stay dry from sweat, resistant to odors, and comfortable at the right body temperature 365 days a year.
Classic All-Season Merino
Our most versatile year-round fabric features a nylon core for durability, while keeping soft 100% Merino wool next to skin.
Classic Thermal Merino
This Base Layer
Made with 100% Merino wool for natural sweat management, odor-resistance, and temperature regulation.
Intraknit™ All-Season Merino
Our 3D-knit base layer features a fabric that combines natural benefits of Merino wool with softness and cooling properties of TENCEL™.
Intraknit™ Thermal Max Merino
Our Intraknit™ technology is helping revolutionize the base layer industry. Including 3D-mapping for a custom fit, durability, and freedom to move.
Intraknit™ Thermal Merino
Our most advanced performance base layer is 3D-knit to provide a tailored fit with mesh ventilation to balance warmth and breathability.
Features
Slim
Our slim fit is intended to follow the contours of the body
Fabric helps combine the moisture management, temperature regulation, and odor resistance of 100% Merino wool with interlock knit for comfort
Flatlock seam construction designed to help increase comfort and minimize chafing
Fully functional fly
Merino-lined elastic waistband designed for comfort
100% Merino next to skin
Size medium inseam: 21.5" (55 cm)
Made in Vietnam: 100% Merino Wool. Exclusive of Decoration.
SW016365
Care
Machine Wash Warm Gentle cycle
Wash With LikeColors
Do Not Bleach
Tumble Dry Low
Cool Iron As Needed
Do Not Iron Decoration
Do Not Dry Clean
Men's Classic Thermal Merino Base Layer 3/4 Bottom
$115.00
The Breakdown
Comfortable in the uncomfortable.
Classic Thermal
Our fan favorite base layer made from 100% ZQ Merino wool. Ideal for cold-weather activities where warmth and breathability are crucial.
Moisture Management
Technology
Odor Resistant
Technology
Body Temp Regulation
Technology
100% Merino Wool
Fabric
Start-Stop
Activity
Cold
Temperature
Size Guide
InCm
Size Chart
Size
XS
S
M
L
XL
XXL
3XL
Chest
32″–34″ 81.5–86.5cm
35″–37″ 89–94cm
38″–40″ 96.5–101.5cm
41″–43″ 104–109cm
44″–46″ 112–117cm
47″–49″ 119.5–124.5cm
50″–52″ 127–132cm
Waist
25″–27″ 63.5–68.5cm
28″–30″ 71–76cm
31″–33″ 78.5–84cm
34″–36″ 86.5–91.5cm
37″–39″ 94–99cm
40″–42″ 101.5–106.5cm
43″–45″ 109–114.5cm
Hip
34″–36″ 86.5–91.5cm
37″–39″ 94–99cm
40″–42″ 101.5–106.5cm
43″–45″ 109–114.5cm
46″–48″ 117–122cm
49″–51″ 124.5–129.5cm
52″–54″ 132–137cm
High Hip
31″–33″ 78.5–84cm
34″–36″ 86.5–91.5cm
37″–39″ 94–99cm
40″–42″ 101.5–106.5cm
43″–45″ 109–114.5cm
46″–48″ 117–122cm
49″–51″ 124.5–129.5cm
Arm Length
30″–31″ 76–78.5cm
31″–32″ 78.5–81.5cm
32″–33″ 81.5–84cm
33″–34″ 84–86.5cm
34″–35″ 86.5–89cm
35″–36″ 89–91.5cm
36″–37″ 91.5–94cm
Inseam
29″–30″ 73.5–76cm
30″–31″ 76–78.5cm
31″–32″ 78.5–81.5cm
32″–33″ 81.5–84cm
33″–34″ 84–86.5cm
34″–35″ 86.5–89cm
35″–36″ 89–91.5cm
Neck
13″–13.5″ 33–34.5cm
14″–14.5″ 35.5–37cm
15″–15.5″ 38–39.5cm
16″–16.5″ 40.5–42cm
17″–17.5″ 43–44.5cm
18″–18.5″ 45.5–47cm
19″–19.5″ 48–49.5cm
Weight
100–130 lbs 45–59kg
130–155 lbs 59–70kg
155–180 lbs 70–82kg
180–210 lbs 82–95kg
210–240 lbs 95–109kg
240–270 lbs 109–122kg
270–300 lbs 122–136kg
Height
5′3″–5′5″ 160–165cm
5′5″–5′7″ 165–170cm
5′7″–5′9″ 170–175cm
5′9″–5′11″ 175–180cm
5′11″–6′1″ 180–185cm
6′1″–6′3″ 185–190cm
6′3″–6′5″ 190–196cm
Numeric Size
0–2
4–6
8–10
12–14
16–18
20–22
24–26
Letter Size
XS
S
M
L
XL
2XL
3XL
Size
1X
2X
3X
4X
Chest
…
…
…
…
Fit
Slim Fit
Follows the contour of the body.
Regular Fit
Room to move without additional bulk.
Relaxed Fit
Offers more room without being baggy.
How to Measure
1. Chest
Measure under the arms, around the fullest part of your chest and back circumference.
2. Waist
Measure around your natural waistline. Keep the measuring tape comfortably loose.
3. High Hip
Measure around high hip circumference approximately 3 inches below natural waistline.
4. Hip
Measure around the fullest part of hip circumference, parallel to the floor.
5. Arm Length
With elbow bent slightly, measure from center back of neck, across top of shoulder, to elbow and down to wrist bone.
6. Inseam
Measure along the inside of the leg from crotch to ankle bone. Or measure a well-fitting base layer from crotch seam to pant leg bottom.
Find the size that fits you best based on people just like you.
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Free Returns
Free Return Policy Smartwool offers free returns within 30 days from the date of purchase. Items must be unused, unwashed, and unaltered.
Store Returns Return the unworn item(s) to the store where you originally made the purchase for a refund or exchange.
Online Returns Return unworn item(s) purchased at smartwool.com 30 days from the date of purchase for a complete refund. Initiate a return by accessing your order history and selecting “Return Items."
Refunds may take up to 3-5 weeks to process due to the time often required for shipping and bank processing. Exchanges are not available.
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Free Shipping
We are currently offering free shipping on orders $89+ placed on smartwool.com.
Shipping based on normal carrier restrictions and delays. We cannot guarantee arrival. Offer is valid for the continental US excluding Alaska, Hawaii, Puerto Rico and any US territories, as well as PO Box addresses. Delivery days are Monday-Friday, excluding US federal holidays. Free shipping may not be available for some customers.
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