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Smartwool Classic Thermal Merino Base Layer Bottom vs KUIU ULTRA Merino 160 Bottom

Buy the Smartwool Classic Thermal if you want maximum warmth and pure merino next to skin for skiing, winter hiking or cold-weather layering. Buy the ULTRA Merino 160 if you want a lighter, faster-drying bottom for active hunts and multi-day wear where durability and shape retention matter. The Smartwool is the warmer and more naturally odor-resistant of the two; the ULTRA blends in polyester for strength and stretch recovery and rates highly with owners on fit and durability.

  • Choose the Smartwool Classic Thermal if you run cold, ski or hike in frigid conditions, and prefer an all-merino fabric against your skin.
  • Choose the ULTRA Merino 160 if you want a lighter base layer for high-output days and extended wear, and value a blend built to hold its shape.

Prices

  • Smartwool Classic Thermal Merino Base Layer Bottom: $115.00 at Jenson USA (last seen Nov 9)
  • KUIU ULTRA Merino 160 Bottom: $89.00 at KUIU (checked today)
  • Difference: the KUIU ULTRA Merino 160 Bottom is $26.00 cheaper than the Smartwool Classic Thermal Merino Base Layer Bottom at the latest prices (Nov 9 and Nov 10)
Smartwool
Smartwool Classic Thermal Merino Base Layer Bottom Men's

Smartwool Classic Thermal Merino Base Layer Bottom

Smartwool Classic Thermal Merino Base Layer Bottom Men's

5(9 ratings)
$115.00at Jenson USAChecked Nov 9
See all prices and details
Visit Jenson USA
Pros
  • Warmest-weight 100% merino for serious cold
  • Interlock knit regulates temperature and resists odor
  • Flatlock seams and merino-lined waistband reduce chafe
  • Fully functional fly
Cons
  • Pure merino is less abrasion-resistant than a blend
  • Slim fit runs close; size up if you want room
  • Longer inseam than some shoppers want
ULTRA
ULTRA Merino 160 Bottom

KUIU ULTRA Merino 160 Bottom

ULTRA Merino 160 Bottom

4.8(592 ratings)
$89.00at KUIUChecked 7 h ago
See all prices and details
Visit KUIU
Pros
  • Lighter and less bulky under layers
  • Polyester blend holds shape and resists stretching out
  • Crotch gusset and flatlock seams for comfort
  • Strong owner ratings for fit and durability
Cons
  • Less warm than a 250 g/m² merino bottom
  • Blend has less pure-merino feel next to skin
  • Shorter 28-inch inseam

What separates them

Smartwool Classic Thermal Merino Base Layer BottomKUIU ULTRA Merino 160 Bottom
Fabric weight250 g/m² midweight, Smartwool's warmest base layer weight160 g/m² lightweight
Fiber content100% merino wool67% merino, 33% polyester (Nuyarn)
Warmth for cold conditionsWarmer; built for frigid days and low-output coldRated cold to frigid but lighter, better for active output
Durability and shape retentionPure merino can stretch and wear faster with hard usePolyester blend resists stretching out and abrasion
InseamAbout 30.5 in on a medium28 in
FitSlim, follows body contoursFitted next-to-skin
Moisture and odorInterlock knit manages moisture and odor naturallyNuyarn merino with odor resistance and good wicking
Owner feedbackLong-standing reputation for warmth and comfort4.8 of 5 from 592 ratings, praised for fit and durability

Price history

$125.00$89.00
Nov 6Nov 9
  • Smartwool Classic Thermal Merino Base Layer Bottom: lowest $115.00 on Nov 9 at Jenson USA.
  • KUIU ULTRA Merino 160 Bottom: lowest $89.00 on Nov 9 at KUIU.

Prices at every store

Smartwool Classic Thermal Merino Base Layer Bottom

  • Ski ShackNew

    In stock

    $115.00Checked Nov 9
    Visit Ski Shack
  • Jenson USANew

    In stock

    $115.00Free shippingChecked Nov 9
    Visit Jenson USA
  • Outdoor Gear ExchangeNew

    In stockReturn policy

    $125.00Checked 7 h ago
    Visit Outdoor Gear Exchange
  • Backcountry.comNew

    In stock

    $125.00Free shippingChecked Nov 9
    Visit Backcountry.com

Also available at

  • evoCheck price at evo
  • The Basin LodgeCheck price at The Basin Lodge
  • Miyar AdventuresCheck price at Miyar Adventures
All 17 stores and price history →

KUIU ULTRA Merino 160 Bottom

  • KUIUNew

    In stockReturn policy

    $89.00Checked 7 h ago
    Visit KUIU

Also available at

  • KUIUCheck price at KUIU
Prices and history →

Specs compared

SpecSmartwool Classic Thermal Merino Base Layer BottomKUIU ULTRA Merino 160 Bottom
FitSlimFitted Base Layer, 28-inch inseam
Weight0.208 kgs5.9 oz / 167 g (L)
Fabric weightMidweight: 250g/m2—
Merino content100% Merino Wool—
Inseam size medium30.5" (77.5 cm)—
Country of manufactureVietnam—
Waistmid-rise waist—
Inseam30 in—
Waist measurement27 in—
Outseam40 1⁄2 in—
Material—67% Merino Wool / 33% Polyester- 160 g/m²
Inseam Length—28″
Show all 14 specsShow fewer specs
SpecSmartwool Classic Thermal Merino Base Layer BottomKUIU ULTRA Merino 160 Bottom
Best Use—Base Layer
Protection—Naturally Odor Resistant

What reviewers say

Smartwool Classic Thermal Merino Base Layer Bottom

Owners of Smartwool's 250-weight merino bottoms generally praise the warmth-to-weight ratio, odor control and next-to-skin softness. Common complaints center on durability and the slim cut.

What people mention
  • WarmthPraisedOwners say the 250 g/m2 merino keeps legs warm on cold ski and hike days without bulk.
  • Odor controlPraisedWearers report it stays fresh across multiple days, unlike synthetic baselayers.
  • FitMixedThe slim cut layers well for some, but others find it tighter than expected and size up.
  • DurabilityCriticisedSome owners report thin spots and wear at the knees and seat after a season or two.

KUIU ULTRA Merino 160 Bottom

  • 4.8 / 5592 ratings

Buyers rate it highly, calling it soft, lightweight and warm for cold weather. The fit and odor resistance draw the most praise, and owners describe it as high quality and not constraining.

What people mention
  • FitPraisedOwners say it fits well and stays comfortable all day without feeling tight.
  • ComfortPraisedBuyers describe the fabric as soft and not constraining next to skin.
  • WarmthPraisedReviewers say it keeps them warm in cold weather as a base layer.

Questions and answers

Which is warmer, the Smartwool Classic Thermal or the ULTRA Merino 160?
The Smartwool is warmer. Its 250 g/m² all-merino fabric is a midweight built for frigid days, while the ULTRA is a 160 g/m² lightweight meant for active wear.
Which lasts longer?
The ULTRA's merino-polyester blend resists stretching out and abrasion better than pure merino. The Smartwool feels plusher but pure wool wears faster with hard use.
Which is better for hunting?
The ULTRA was designed for extended hunts, with a gusset, flatlock seams and a blend that keeps its shape over multi-day wear. The Smartwool suits cold sits and slow days.
Is the ULTRA worth stepping up to over the Smartwool?
Step up to the ULTRA if you want a lighter, more durable layer for high-output activity. Stay with the Smartwool if warmth is your priority.
How does the fit compare?
Both are fitted. The Smartwool is slim with a 30.5-inch inseam on a medium; the ULTRA is next-to-skin with a 28-inch inseam.
Does either resist odor?
Both do. The Smartwool relies on 100% merino, and the ULTRA uses Nuyarn merino, which is naturally odor resistant.

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OdorPraised
Owners report it stays fresh over extended wear thanks to the merino.