How to Choose Base Layers

A synthetic base layer for moderate temps, the women's REI Co-op Lightweight Long-Sleeve Crew keeps you dry and comfortable whether you're venturing into the mountains or trekking across open desert.
Imported.
View all REI Co-op Women's Base Layer TopsBest Use | Multisport |
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Shirt Type | T-shirt |
Fabric | 94% recycled polyester/6% spandex (bluesign approved) |
Sun-Protective Fabric | Yes |
UPF Rating | 50+ |
Moisture Wicking | Yes |
Quick Drying | Yes |
Underwear Weight | Lightweight |
Sleeve Length | Long Sleeve |
Gender | Women's |
Sustainability | Contains materials that meet the bluesign® criteria Contains recycled materials Fair Trade Certified™ factory From a Climate Label Certified brand |
XXS | XS | S | M | L | XL | 1X | 2X | 3X | 0 | 2 | 4 | 6 | 8 | 10 | 12 | 14 | 16 | 18W | 20W | 22W | 24W | 26W | |
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Numerical Size | 00 | 0-2 | 4-6 | 8-10 | 12-14 | 16 | 18 | 20-22 | 24-26 | 0 | 2 | 4 | 6 | 8 | 10 | 12 | 14 | 16 | 18 | 20 | 22 | 24 | 26 |
Bust | 31 | 32-33 | 34-35 | 36-37 | 38.5-40 | 41-42.5 | 43-45 | 47-49 | 51-53 | 32 | 33 | 34 | 35 | 36 | 37 | 38.5 | 40 | 42.5 | 45 | 47 | 49 | 51 | 53 |
Sleeve Length | 29.5 | 30 | 30.5 | 31 | 31.5 | 32 | 32.5 | 33.5 | 34.5 | 30 | 30 | 30.5 | 30.5 | 31 | 31 | 31.5 | 31.5 | 32 | 32.5 | 33.5 | 33.5 | 34.5 | 34.5 |
Waist | 24.5 | 25.5-26.5 | 27.5-28.5 | 29.5-30.5 | 32-33.5 | 34.5-36.5 | 37.5-39.5 | 40.5-42.5 | 44.5-46.5 | 25.5 | 26.5 | 27.5 | 28.5 | 29.5 | 30.5 | 32 | 33.5 | 36 | 38.5 | 40.5 | 42.5 | 44.5 | 46.5 |
Hip | 34 | 35-36 | 37-38 | 39-40 | 41.5-43 | 44-46 | 47-49 | 50-52 | 54-56 | 35 | 36 | 37 | 38 | 39 | 40 | 41.5 | 43 | 45.5 | 48 | 50 | 52 | 54 | 56 |
Inseam | 31 | 31 | 31 | 31 | 31 | 31 | 31 | 31 | 31 | 31 | 31 | 31 | 31 | 31 | 31 | 31 | 31 | 31 | 31 | 31 | 31 | 31 | 31 |
Measurements are stated in inches unless otherwise indicated. Size chart values represent body measurements, not garment measurements. Some women's pants are available in petite and tall sizes. Typically petite sizes fit women 4'11" to 5'3". Regular sizes fit women 5'4" to 5'8". Tall sizes fit women 5'9" to 5'11".
PETITE: Generally, as compared to regular sizes, petite sizes are 2.5 inches shorter in inseam, 1 inch shorter in body length, 1.25 inches shorter in sleeve length and ¾ inch shorter in total rise.
TALL: tall sizes are 3 inches longer in inseam, 2 inches longer in body length, 2.5 inches longer in sleeve length and 1.25 inches longer in total rise.
Capri or cropped pants have an intentionally shorter inseam—reference the technical specs instead of this chart.
Inseam is measured to the floor.
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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I really like this base layer top, a great choice for spring weather. It is soft and comfortable to wear next to my skin, I like the heathered color. I wear it for hiking and doing volunteer trail work. While wearing it on a hike I got caught in a brief rain shower, the top got damp but was dry in a couple of hours. To check the “ stink factor “ I wore it 3 days in a row, one day hiking with friends and 2 days doing trail work. It was very dirty at the end of the last day but not stinky at all and washed up well. Makes me think it would be a great layer for backpacking . In this 50s degree weather it goes well under a vest, I will be wearing this top a lot!
I feel like most REI brand clothing I end up loving and this is no exception. I live in a climate that has cool morning, warm afternoons, and chilly evenings and this shirt is perfect for all temperatures. I've used it as a base layer when it has been on the cooler side, but I also just like it as a shirt. I have a softshell vest that I love pairing this with since I don't really need something heavy, but something to keep the chill off me in the morning, but light enough to leave on when the afternoons warm. I also find the material to be very comfortable, it is silky and soft, it has worn well with washing and they color (the purple one) is great. I wear a lot of back, so having the soft lavender color gave me a new piece to rotate in my daily wear. This shirt doesn't really have a lot of bells and whistles, but it is perfect as a base layer or a primary one! I'm going to order a couple more in some other colors!
I was excited to try this top because after testing a different REI top (the REI Active Pursuits T-shirt), I ordered five more and recommended them to friends. This base layer feels pretty similar at 94% polyester/6% spandex vs the other shirt at 92%/8%. I actually feel the REI Active Pursuits T-shirt breathes slightly better, but they are pretty similar in softness and breathability. Overall, my favorite thing about this top is that it's a true-to-size, flattering fit that is long enough that I can move around, squat down, and reach for things while out hiking without my shirt pulling up on me. It's thin enough and snug enough that I can easily layer it under clothing, but looks good as a standalone top. I also like that that sleeves easily pull up on my elbows as I get warmed up on a long hike. It is very comfortable under a backpack - doesn't pull or irritate the skin like some tops can under a backpack, for my sensitive skin. I took it out on cool 50-degree mornings and walked across the Great Salt Lake in it under the blazing sun. It stayed cool and comfortable.
This is a great base layer for cool weather hikes or chili evenings. The fabric is soft and non chaffing and is very quick drying. While the fit is not flattering for full figures, I would recommend this product based on function, and the color is pretty too!
This is a nice layering shirt. Small fits well with some room if you wanted to add something under as well. Nice color doesn't hurt either.
I love the long sleeve athletic shirt. I play pickleball in warm weather and this lightweight shirt gives coverage but is not too hot.
I received these products for free from the REI Trailblazers sampling program in exchange for my honest review. I received this gray synthetic workout top. I normally wear a size medium and this size medium fits great. I'm 5'3 130 lb with an athletic upper body. A lot of REI shirts fit me quite well, I appreciate the room in the shoulders. Other products run quite small I have found that are even meant for hiking. So I really appreciate that REI makes good quality clothes that actually fit athletic individuals who do hiking and backpacking. The material of the shirt is very soft. It washed up excellent. It does hold odor quite well in the seams so for multi-day trips it would not be good. But as long as you're coming home and washing it it should be great. I would definitely recommend this shirt to any friends who are looking for a high quality lightweight workout shirt. #reitrailblazers!
The ideal seasonal transition top. For all-day activities, the long-sleeve crew layers for cool mornings and shines solo when the temperature heats up. Moisture wicking with a tapered fit and shaped hem — wear it tucked, or not! — it’s comfortable from trail to town. The hang loop is a convenient touch and the UPF 50+ sun protection gives added confidence during sunny, blue-sky days.
Simply the BEST crew I have ever owned. The fit is perfect and is flattering to my shape. Love the style and fabric - easy care and performance - totally light-weight and great for all seasons. These crews are my go-to shirt.