Women's Classic Thermal Merino Base Layer Crew
Smartwool

Women's Classic Thermal Merino Base Layer Crew

Smartwool's warmest everyday Merino crew, with shoulder panels that keep seams off your pack straps.

$125
Color: Black
Also inMen'sUnisex
Size:
Size guide
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Top features
100% ZQ Merino wool
Moisture management
Midweight 250 g/m² interlock knit
Description

Meet the new and improved Women's Classic Thermal Merino Base Layer Crew. We've updated this 100% Merino wool fan-favorite with new color options and an enhanced fit to improve functionality while elevating aesthetics. The addition of shoulder panels and its flatlock seam construction helps prevent chafing and increases your comfort level. Add one of our best base layers for cold weather to your winter wardrobe and experience the difference the next time you go skiing, hiking, climbing, or biking.

Perfect for
Ski and ride
Under a shell.
Hike and climb
Cold-weather days.
ZQ Merino
Certified wool.
Features
  • 100% ZQ Merino wool. Smartwool sources this fabric through the New Zealand Merino Company's ZQ programme, which covers animal welfare, environmental and social standards.
  • Moisture management. Merino moves moisture as vapor before it becomes sweat on the skin, so you stay drier under a midlayer on start-stop days.
  • Midweight 250 g/m² interlock knit. The Classic Thermal weight — built for cool to cold weather rather than high-output summer use.
  • Shoulder panels and flatlock seams. Shoulder panels move the seam off the top of the shoulder, where a pack strap sits, and flatlock construction keeps every seam flat against the skin.
  • Raglan sleeves. Raglan sleeves and a back body seam that wraps to the front give the arms an unbroken range of motion for reaching and climbing.
Size & Fit
Slim
Regular
Relaxed

Close to the body. Size up if you're between sizes or want room to layer underneath.

Slim fit, intended to follow the contours of the body. Take your usual size for a close base-layer fit; size up if you want more room through the body or plan to layer underneath. Raglan sleeves and shoulder panels move seams away from the top of the shoulder, so a pack strap does not sit on one. Offered XS to XL.

Open size guide
Materials
  • 100% Merino wool (exclusive of decoration and elastic).
  • Care: Machine wash cold on gentle cycle with like colors; do not bleach; tumble dry low or lay flat to dry; do not iron; do not dry clean.
About the brand

Smartwool brings the magic of merino wool to life — keeping you warm, dry, and comfortable no matter the season. From performance socks to base layers, every piece is designed for adventure. At Mountain Sports, we love Smartwool because it proves comfort and sustainability can go hand in hand, from trail to town.

Shop all Smartwool

SKU SW016369-001 · Style SW016369
Size guide

Smartwool Size Chart - Women's Apparel

Smartwool Sizing Chart

Measurements are in inches, unless otherwise noted. Charts reflect body measurements, not garment measurements.

Women's Apparel & Base Layers:

Size Numeric Size Equivalent Chest Waist High Hip Hip Inseam Arm Length
XS 0 - 2 32 - 33 24 - 25 31 - 32 35 - 36 29 - 30 27 - 28
S 4 - 6 34 - 35 26 - 27 33 - 34 37 - 38 30 - 31 28 - 29
M 8 - 10 36 - 38 28 - 30 35 - 36 39 - 40 31 - 32 29 - 30
L 12 - 14 39 - 40 31 - 34 37 - 39 41 - 43 32 - 33 30 - 31
XL 16 - 18 41 - 44 35 - 38 40 - 43 44 - 47 33 - 34 31 - 32

Women's Plus Sizes:

Size Numeric Size Equivalent Chest Waist High Hip Hip Inseam Arm Length
1X 16 - 18 43 - 45 39 - 41 44 - 46 45 - 47 30 - 32 31
2X 20 - 22 47 - 49 43 - 46 48 - 50 49 - 51 30 - 32 31
3X 24 - 26 51 - 53 47 - 50 52 - 54 53 - 55 30 - 32 32
4X 28 - 30 55 - 57 52 - 55 56 - 58 57 - 59 30 - 32 33

How to measure - Chest: measure under the arms, around the fullest part of your chest and back. Waist: measure around your natural waistline, keeping the tape comfortably loose. High hip: measure around your high hip, approximately 3 inches below your natural waistline. Hip: measure around the fullest part of your hip, parallel to the floor. Inseam: measure along the inside of the leg from crotch to ankle bone, or measure a well-fitting base layer pant from the crotch seam to the bottom of the leg. Arm length: with your elbow slightly bent, measure from the center back of your neck, across the top of your shoulder, to the elbow and down to the wrist bone.

Smartwool clothing runs true to size. Smartwool products are designed to retain their fit and shape; following the care instructions on the label will help avoid shrinking or stretching.
Performance

How it ranks across conditions.

Calibrated against comparable products we stock, so you can compare like for like.

Warmth

Light
Midweight
Warm
Very warm

At 250 g/m² this is Smartwool's Classic Thermal weight — their warmest everyday Merino base layer fabric, positioned for cool to cold conditions.

Breathability

Low
Moderate
High
Very high

Merino breathes well for its warmth, but a 250-weight knit is denser than a 150 — expect to run warm on high-output days above freezing.

Odor resistance

Low
Moderate
High
Excellent

Merino resists odor build-up naturally, which is what makes a wool crew wearable for several days on a hut trip.

Fit

Compression
Slim
Standard
Relaxed

Smartwool's slim fit follows the contours of the body so it layers cleanly under a midlayer or shell without bunching.

Best for

Is this right for you?

Ski and snowboard days

Smartwool's own label for this weight is start-stop activity — exactly what a lift day is. Warm on the chair, breathable enough on the way down.

Not for: For sustained high-output cold-weather effort like skinning laps, Smartwool points to their Intraknit line instead. Pair it with the Classic Thermal Bottom

Cold-weather hiking and climbing

Shoulder panels keep seams off the top of the shoulder where a pack strap sits, and the raglan sleeve leaves the arms free to reach.

Not for: A crew neck cannot be vented. If you run hot and stop and start a lot, a quarter-zip gives you a way to dump heat. Try the Classic Thermal 1/4 Zip

Everyday winter layering

Clean enough to wear on its own under a coat, and odor-resistant enough to go several days between washes on a trip.

Not for: Above about 50°F this is more wool than most people want against the skin all day. Pair it with the Classic Thermal Bottom

Full spec sheet

Technical Specs

Material100% Merino wool, exclusive of decoration and elastic
Fabric weightMidweight — 250 g/m²
Garment weight218 g (7.69 oz)
FitSlim — follows the contours of the body
NecklineCrew
ConstructionRaglan sleeves, shoulder panels, flatlock seams, back body seam wraps to front
Country of originMade in Vietnam
Style numberSW016369
Questions, answered

Before you buy.

Pulled from chats, emails and store visits. The things people actually ask us before they buy. Don't see yours?

Ask a question
How does the 250 weight compare to Smartwool's 150?

The 150 (Classic All-season) is a lightweight 150 g/m² fabric Smartwool positions for warm to cool weather — worn alone on warm days, as a layering foundation on cooler ones. This Classic Thermal is 250 g/m² and is made for cool to cold weather. If most of your days are above freezing and high-output, the 150 is the better pick.

Do the shoulder panels actually matter?

Yes, if you carry a pack. Shoulder panels move the seam off the top of the shoulder, which is exactly where a pack strap or a climbing harness's gear loops bear down. Combined with the raglan sleeve and flatlock construction, there is no seam sitting under load.

Do these run true to size?

Smartwool builds this in a slim fit intended to follow the contours of the body, sized to their standard women's chart. Take your usual size for a close base-layer fit. Size up if you want more room through the body or plan to wear something underneath.

Will 100% Merino hold up to regular washing?

Yes, with reasonable care. Machine wash warm on a gentle cycle and tumble dry low or lay flat. Skip fabric softener — it coats the fiber and blunts the wool's moisture management. Merino also needs washing far less often than synthetic, so it sees the machine less to begin with.

What does ZQ certified wool mean?

ZQ is a wool certification developed by the New Zealand Merino Company, covering animal welfare, environmental management and social standards on the farms that supply the fiber. Smartwool states that practices which cause harm, such as mulesing, are never permitted under it.

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