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Men's Underwear

(178 products)

Products (178)

Sort: Best Match

Top Rated
REI Co-opMerino 185 Long-Sleeve Base Layer Top - Men's
$39.83 - $79.95
174 reviews with an average rating of 4.5 out of 5 stars
Underwear Weight:
Lightweight
Size Type:
Regular, Big
Top Rated
REI Co-opMidweight Base Layer Half-Zip Top - Men's
$29.83 - $59.95
142 reviews with an average rating of 4.6 out of 5 stars
Underwear Weight:
Midweight
Size Type:
Regular, Big, Tall
REI Co-opEveryday Boxer Briefs - Men's
$22.95
145 reviews with an average rating of 4.2 out of 5 stars
Size Type:
Regular, Big
Free FlyElevate Boxer Briefs - Men's
$28.73
Save 24%
compared to $38.00
54 reviews with an average rating of 4.0 out of 5 stars
Size Type:
Regular, Big
REI OUTLET
SaxxKinetic Light-Compression Mesh Boxer Brief
$28.73
Save 24%
compared to $38.00
0 reviews
Size Type:
Regular
REI OUTLET
Top Rated
REI Co-opMidweight Long-Sleeve Base Layer Top - Men's
$37.93 - $54.95
155 reviews with an average rating of 4.5 out of 5 stars
Underwear Weight:
Midweight
Size Type:
Regular, Big, Tall
Top Rated
REI Co-opMerino 185 Long-Sleeve Half-Zip Base Layer Top - Men's
$49.83 - $89.95
102 reviews with an average rating of 4.6 out of 5 stars
Underwear Weight:
Lightweight
Size Type:
Regular, Big
Top Rated
Arc'teryxRho LT Zip-Neck Base Layer Top - Men's
$84.93 - $120.00
91 reviews with an average rating of 4.6 out of 5 stars
Underwear Weight:
Lightweight
Size Type:
Regular, Big
SaxxVibe Super Soft Boxer Briefs - Men's
$25.73
Save 24%
compared to $34.00
27 reviews with an average rating of 4.0 out of 5 stars
Size Type:
Regular, Big
REI OUTLET
Top Rated
REI Co-opLightweight Long-Sleeve Crew Base Layer Top - Men's
$39.95
9 reviews with an average rating of 4.7 out of 5 stars
Underwear Weight:
Lightweight
Size Type:
Regular, Big, Tall
Top Rated
REI Co-opLightweight Base Layer Bottoms - Men's
$39.95
11 reviews with an average rating of 4.8 out of 5 stars
Underwear Weight:
Lightweight
Size Type:
Regular, Big, Tall
Top Rated
SmartwoolClassic All-Season Merino Long-Sleeve Base Layer Top - Men's
$66.93 - $90.00
66 reviews with an average rating of 4.5 out of 5 stars
Underwear Weight:
Lightweight
Size Type:
Regular, Big
SmartwoolClassic All-Season Merino T-Shirt - Men's
$59.93 - $80.00
75 reviews with an average rating of 4.1 out of 5 stars
Underwear Weight:
Lightweight
Size Type:
Regular, Big
Top Rated
SmartwoolClassic Thermal Merino Base Layer Bottoms - Men's
$115.00
617 reviews with an average rating of 4.7 out of 5 stars
Underwear Weight:
Midweight
Size Type:
Regular, Big
Top Rated
REI Co-opLightweight Crew Base Layer Top - Men's
$29.95
17 reviews with an average rating of 4.5 out of 5 stars
Underwear Weight:
Lightweight
Size Type:
Regular, Big, Tall
Top Rated
PatagoniaCapilene Midweight Base Layer Bottoms - Men's
$59.93 - $89.00
56 reviews with an average rating of 4.5 out of 5 stars
Underwear Weight:
Midweight
Size Type:
Regular, Big
Top Rated
SmartwoolClassic Thermal Merino Crew Base Layer Top - Men's
$69.83 - $115.00
1506 reviews with an average rating of 4.7 out of 5 stars
Underwear Weight:
Midweight
Size Type:
Regular, Big
REI Co-opMidweight Base Layer Bottoms - Men's
$54.95
77 reviews with an average rating of 4.4 out of 5 stars
Underwear Weight:
Midweight
Size Type:
Regular, Big, Tall
REI Co-opMerino 185 Base Layer Bottoms - Men's
$79.95
129 reviews with an average rating of 4.3 out of 5 stars
Underwear Weight:
Lightweight
Size Type:
Regular, Big
Top Rated
PatagoniaCapilene Midweight Crew Base Layer Top - Men's
$59.93 - $89.00
79 reviews with an average rating of 4.5 out of 5 stars
Underwear Weight:
Midweight
Size Type:
Regular, Big
Top Rated
Arc'teryxRho LT Crew Neck Base Layer Top - Men's
$70.93 - $100.00
28 reviews with an average rating of 4.8 out of 5 stars
Underwear Weight:
Lightweight
Size Type:
Regular, Big
tasc PerformanceElevation Merino T-Shirt - Men's
$49.73
Save 37%
compared to $79.00
38 reviews with an average rating of 4.2 out of 5 stars
Underwear Weight:
Lightweight
Size Type:
Regular, Big
REI OUTLET
StanceSandy Beach Boxer Briefs - Men's
$19.73
Save 26%
compared to $27.00
1 reviews with an average rating of 5.0 out of 5 stars
Size Type:
Regular
REI OUTLET
Top Rated
PatagoniaCapilene Midweight Zip-Neck Base Layer Top - Men's
$69.93 - $99.00
61 reviews with an average rating of 4.6 out of 5 stars
Underwear Weight:
Midweight
Size Type:
Regular, Big
Top Rated
IcebreakerMerino 200 Oasis Long-Sleeve Crewe Thermal Top - Men's
$72.93 - $105.00
134 reviews with an average rating of 4.7 out of 5 stars
Underwear Weight:
Midweight
Size Type:
Regular, Big
REI Co-opMerino 185 Base Layer Top - Men's
$69.95
53 reviews with an average rating of 4.2 out of 5 stars
Underwear Weight:
Lightweight
Size Type:
Regular, Big
Arc'teryxRho LT Base Layer Bottoms - Men's
$49.83 - $100.00
48 reviews with an average rating of 4.5 out of 5 stars
Underwear Weight:
Lightweight
Size Type:
Regular, Big
SmartwoolClassic All-Season Merino Quarter-Zip Base Layer Top - Men's
$70.93 - $95.00
4 reviews with an average rating of 4.8 out of 5 stars
Underwear Weight:
Midweight
Size Type:
Regular, Big
PatagoniaCapilene Thermal Weight Zip-Neck Top - Men's
$69.93 - $109.00
18 reviews with an average rating of 4.0 out of 5 stars
Underwear Weight:
Heavyweight
Size Type:
Regular, Big
tasc PerformanceElevation Merino Base Layer Bottoms - Men's
$49.73
Save 37%
compared to $79.00
31 reviews with an average rating of 3.8 out of 5 stars
Underwear Weight:
Lightweight
Size Type:
Big, Regular
REI OUTLET

1–30 of 178 products

Sort: Best Match

Related Expert Advice articles

What material is best?

Wool is moisture-wicking and odor-resistant, while synthetic fabrics are more durable and less expensive.

Match the temp to the trek

Lightweight layers are best for moderate to cool temperatures. Midweight layers are best for cold temperatures. Heavyweight layers are best for below-freezing temperatures.

Find your fit

To be able to wick sweat efficiently, your next-to-skin layer needs to actually be next to your skin. A comfortably snug fit everywhere is your goal.

Read full article: How to Choose Base Layers

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