How to Choose Base Layers
REI Co-op Lightweight Base Layer Bottoms - Men's
This product is not available. Good news: we have a newer version.
These REI lightweight base layer bottoms are designed to keep you warm and wick away moisture during high-performance outdoor activities when the temperature starts to drop.
Shop newer version- Soft polyester fabric wicks moisture and dries quickly
- Mineral-based LAVA XLâ„¢ finish keeps fabric odor-free
- Flatseam construction and low-profile waistband and crotch gusset keep you comfortable as you move
- Fly opening
- Fitted
- REI Co-op brand is certified to The Climate Label; we actively fund efforts to reduce carbon emissions across our business and support climate projects around the world
Imported.
View all REI Co-op Men's Base Layer Bottoms| Best Use | Multisport |
|---|---|
| Fabric | Polyester |
| Moisture Wicking | Yes |
| Quick Drying | Yes |
| Fly Opening | Yes |
| Underwear Weight | Lightweight |
| Gender | Men's |
| Sustainability | From a Climate Label Certified brand |
REI Co-op Clothing - Men's
| XS | S | M | L | XL | XXL | XXXL | 24 IN Waist | 26 IN Waist | 28 IN Waist | 30 IN Waist | 31 IN Waist | 32 IN Waist | 33 IN Waist | 34 IN Waist | 35 IN Waist | 36 IN Waist | 38 IN Waist | 40 IN Waist | 42 IN Waist | 44 IN Waist | 46 IN Waist | 48 IN Waist | 50 IN Waist | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Chest | 35 | 36 - 38 | 39 - 41 | 42 - 45 | 46 - 49 | 50 - 53 | 54 - 57 | |||||||||||||||||
| Sleeve Length | 32 | 32.5 | 33 | 33.5 | 34 | 34.75 | 35.5 | |||||||||||||||||
| Waist | 27.5 | 28 - 30 | 32 - 34 | 36 - 38 | 40 - 42 | 44 - 46 | 48 - 50 | 24 | 26 | 28 | 30 | 31 | 32 | 33 | 34 | 35 | 36 | 38 | 40 | 42 | 44 | 46 | 48 | 50 |
| Hip | 33.5 | 34.5 - 36.5 | 37.5 - 39.5 | 41 - 43 | 44 - 46.5 | 47.5 - 50.5 | 51.5 - 54.5 | 32 | 33.5 | 34.5 | 36.5 | 37 | 37.5 | 38.5 | 39.5 | 40.25 | 41 | 43 | 44 | 46.5 | 47.5 | 50.5 | 52.5 | 54.5 |
| Inseam | 32 | 32 | 32 | 32 | 32 | 32 | 32 | 32 | 32 | 32 | 32 | 32 | 32 | 32 | 32 | 32 | 32 | 32 | 32 | 32 | 32 | 32 | 32 | 32 |
Sizing Notes
Measurements are stated in inches unless otherwise indicated. Size chart values represent body measurements, not garment measurements.
SHORT: Some pants are available in short sizes, which generally means an inseam that is 2.5 inches shorter than regular sizes.
TALL: Some pants, shirts, jackets and parkas are available in tall sizes, which generally means an inseam that is 3 inches longer and a rise that is 1 inch longer, a shirt or jacket body that is 2 inches longer, a parka body that is 2.5 inches longer and sleeves that are 2.5 inches longer than regular sizes.
Capri or cropped pants have an intentionally shorter inseam—reference the technical specs instead of this chart.
Inseam is measured to the floor.
Buying Advice
More expert advice
Better gear is built together
From feedback to field testing, all of our gear is dialed-in by REI Co-op members. Their adventures informed every stitch and detail—making for better, longer-lasting gear.
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Most Helpful Favorable Review
57 people found this review helpful
7 years ago
Underwear? I wear these as pants
If you've always wanted to walk out in public in your underwear, but have been a little hesitant to do so... this is the perfect first step. These bad boys keep not only your lower (sometimes better) half warm, but they also make your lazy self look like you just came from the gym. Women in leggings? Meet men in long underwear.
Yes , I recommend this product
SuperMatt
Mesa, AZ, United StatesMost Helpful Critical Review
4 people found this review helpful
6 years ago
Odd fit
I am 5'11" with a 31" waist. The medium was far to baggy and the small was way too tight even on my relatively skinny legs.
No, I do not recommend this product
Marc
7 years ago
Comfortable and Warm
Yes , I recommend this product
I’m using this as a sleepwear baselayer for camping. It is much warmer than you initially expect. The fit is snug but not at all too tight, I love the fit. Also, I have the medium and the weight came in at 5oz. Im very happy with the warmth-to-weight ratio! The REI mid-weight will keep you much warmer since it has a sort of fleece layer below it, but these do an amazing job at its weight. Great product!
Location:Lakeside, CA, United States
8 years ago
Excellent baselayer
Yes , I recommend this product
Part of my hiking gear for a mount Whitney trip on October 3 2017. Sub 30°f temp with winds up to 40mph. Fit was comfortable. Was not scratchy. Remained remarkably comfortable in the the cold weather. Did not feel swampy. Very light.
Location:Mesa, AZ, United States
7 years ago
Underwear? I wear these as pants
Yes , I recommend this product
If you've always wanted to walk out in public in your underwear, but have been a little hesitant to do so... this is the perfect first step. These bad boys keep not only your lower (sometimes better) half warm, but they also make your lazy self look like you just came from the gym. Women in leggings? Meet men in long underwear.
Location:Harrisburg, PA, United States
8 years ago
Great base layer for the price
Yes , I recommend this product
I just didn't feel like spending $50 or $60 on base layer bottoms that the top-shelf competition offers and thus went with these and have no regrets. They seem well-made, are soft/comfortable to wear and the size large fits my 6' 180 pound frame perfectly.
Location:MN
7 years ago
Far warmer than their weight
Yes , I recommend this product
Beats the last two pairs of North Face that i've had, but still way more comfortable, looser, lighter and warmer. Can't explain how, but it works.
Location:Kansas City, MO
7 years ago
Warm & Comfortable
Yes , I recommend this product
Worked extremely well keeping me warm as a baselayer under my shorts. Wind resistance is actually somewhat decent as well. I would go a size down if you’re looking for a more skin-tight fit.
Location:Portland, OR, United States
8 years ago
Warm and lightweight
Yes , I recommend this product
The base layer affords warmth without adding the feel of tight clothing
Location:Columbus, OH, USA
7 years ago
Great base liners
Comfortable and warm. The liners fit well with room to move without binding.
7 years ago
Superbowl tested base layer
Yes , I recommend this product
Light weight and warm that's everything you need in a base layer Tough tested at Super Bowl Experience in Mpls. during coldest day on the Mall
6 years ago
Odd fit
No, I do not recommend this product
I am 5'11" with a 31" waist. The medium was far to baggy and the small was way too tight even on my relatively skinny legs.
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