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REI Co-op Midweight Bottoms Review

A great synthetic thermal long underwear at an unbeatable price for the warmth and durability they provide
rei co-op midweight bottoms long underwear review
Credit: Justin Simoni
Best Buy Award
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Price:  $55 List | $54.95 at REI
Pros:  Tough synthetic fabric, four-way stretch for great range of motion, excellent performance for the price
Cons:  Heavier than wool bottoms for their warmth
Manufacturer:   REI Co-op
By Justin Simoni ⋅ Review Editor  ⋅  Dec 2, 2022
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73
OVERALL
SCORE


RANKED
#3 of 12
  • Warmth - 25% 7.0
  • Breathability - 20% 7.0
  • Comfort and Fit - 20% 7.0
  • Durability - 15% 9.0
  • Drying Speed - 10% 7.0
  • Layering Ability - 10% 7.0

Our Verdict

Simply designed, cozy, and tough enough to keep up, the newly redesigned REI Co-op Midweight Bottoms improves upon its previous version in seemingly every single way. The handsome heathered synthetic fabric is toasty warm and perfect for long winter days. The four-way stretchiness, flatlock seams, and gusseted crotch mean you won't be thinking much about these bottoms while you're moving around your favorite winter landscape, except for how comfortable you are. Washing and general care are straightforward for these bottoms — far easier than a comparable pair of woolies. All this at a price that's hard for others to get even close to.

Editor's Note: This review was updated on December 2, 2022, after testing the most recent version of the Midweight Bottoms.

Compare to Similar Products

 
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Overall Score Sort Icon
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Pros Tough synthetic fabric, four-way stretch for great range of motion, excellent performance for the priceA nice balance of warmth and breathability, super cozy, nicely articulated design100% recycled polyester, light fabric weight, impressive loft and warmthAffordable intro to Merino, warm and cozy, wide spectrum of available sizesUnbeatable price, breathable, quick drying, functional
Cons Heavier than wool bottoms for their warmthExpensive, stretches out in between washes, slow to dry when saturatedQuestionable durability, saggy bottomStarts off slightly itchy, simplified construction may not be as comfy, Merino wool is delicateShort cut legs, average comfort and warmth
Bottom Line A great synthetic thermal long underwear at an unbeatable price for the warmth and durability they provideDesigned to keep you warm in the coldest conditions, this is a versatile pair of Merino wool bottomsWarmer than most and lighter than the rest, this pair of long underwear redefines what is possible from a synthetic base layerGrab a pair of these if you are looking for an affordable and warm pair of Merino wool bottomsSlender and breathable, these are everything we expect out of a lightweight pair of long underwear
Rating Categories REI Co-op Midweight... Smartwool Classic T... Patagonia Capilene... Meriwool Merino 250... REI Co-op Lightweig...
Warmth (25%)
7.0
9.0
6.0
8.0
4.0
Breathability (20%)
7.0
7.0
8.0
6.0
8.0
Comfort and Fit (20%)
7.0
8.0
6.0
7.0
6.0
Durability (15%)
9.0
7.0
8.0
6.0
6.0
Drying Speed (10%)
7.0
7.0
8.0
6.0
7.0
Layering Ability (10%)
7.0
7.0
8.0
6.0
6.0
Specs REI Co-op Midweight... Smartwool Classic T... Patagonia Capilene... Meriwool Merino 250... REI Co-op Lightweig...
Material 100% polyester 100% Merino wool 100% recycled polyester with HeiQ Fresh 100% Merino wool 92% polyester, 8% spandex
Fabric Weight Not stated 250 g/m² 147 g/m² 250 g/m² Not stated
Weight (size medium) 7.4 oz 8.3 oz 5.9 oz 7.9 oz 5.5 oz
Insulation Weight Midweight Midweight Lightweight Midweight Lightweight
3/4 Boot-Cut Available? No Yes No No No
Fly? Yes Yes Yes Yes Yes
Dryer Safe? Yes No Yes No Yes

Our Analysis and Test Results

The REI Midweight Bottoms came out top in warmth for a synthetic and not too far away from the heaviest wool base layers we've tested. They offer a great balance of warmth and breathability and also dry quickly. The four-way stretch fabric makes these a pleasure to wear, whether layering or not. But the real strengths of these bottoms are simply their amazing durability and fantastic price — especially when compared to a comparable wool layer. Probably one of the best-priced pairs of long johns when looking closely at performance, it's not a hard choice to add this layer to your cold-weather wardrobe.

Performance Comparison


rei co-op midweight bottoms long underwear review - worn underneath running tights, this midweight long underwear kept...
Worn underneath running tights, this midweight long underwear kept things toasty, despite the harsh wintry conditions.
Credit: Drew Crittenden

Warmth


These are toasty! The Midweight Bottoms provide great warmth for their weight, only surpassed by much more expensive and slightly heavier wool options. For comparison, our lab tests put these synthetics in approximately the same warmth bracket as a 200 g/m² wool layer.


Generally, we suggest you don't wear too thick of long underwear, as it impedes comfort, fit, and breathability. Better to just put on an additional mid-layer if more warmth is needed. The Midweight Bottoms are a great example of a warm pair of synthetic bottoms that also have a great mix of breathability and comfort.

We tested these for warmth in a variety of situations, including climbing on Longs Peak in Rocky Mountain National Park during cold and windy conditions. We wore them under running tights and while sleeping underneath the stars. In both circumstances, the Midweight passed our warmth anticipations. We found the snug-but-not-tight fit works well with trapping heat and wicking moisture, doing nothing but making these bottoms feel even warmer.

rei co-op midweight bottoms long underwear review - the rei co-op midweight bottoms have a similar warmth as a 200 g/sm...
The REI Co-op Midweight Bottoms have a similar warmth as a 200 g/sm wool bottom, while coming in just a little heavier on the scale.
Credit: Justin Simoni

Breathability


The Midweight Bottoms do a fine job keeping things breathable for their weight. Polyester-based long underwear like these usually perform exemplary in breathability, as the synthetic fabric naturally wicks away excess moisture from the surface of your skin. The snug fit also helps with breathability, aiding the wicking nature of the fabric by ensuring your skin is in contact with the fabric itself.


Keeping dry is important to keep comfortable — especially for long underwear. Changing out of a pair means taking off pants and shoes, which can take time. We're a bit impatient ourselves, so if we can keep comfortable, we'll often choose to keep them on until we get back to the trailhead, even though we may be getting a little toasty.

rei co-op midweight bottoms long underwear review - the snug fit and naturally wicking nature of the polyester synthetic...
The snug fit and naturally wicking nature of the polyester synthetic fabric gives the REI Midweight Bottoms good marks in breathability.
Credit: Justin Simoni

Comfort and Fit


The REI Midweight Bottoms are some of the comfiest synthetic pairs of long underwear we've had the pleasure of testing. The fabric is more smooth than ultra soft, but the four-way stretch really makes them feel wonderful to wear, allowing for great freedom of movement. Minimally obtrusive flatlock seams throughout keep pressure points out of the picture, and we were delighted to find that such a budget pair of midweight leggings still include a gusseted crotch, helping out with the bottom's already excellent articulation.


The cut of the Midweight is neither loose nor tight, and the four-way stretch fabric should allow for a wide spectrum of body types. The inseam is approximately 31" for a size medium and worked well for our main tester, who usually wears a pant with a 32" inseam; the bottom cuff rests just above the ankle. The 1.5" waistband is also approximately 31" around unstretched and didn't feel too tight for a 32" waist. There is a fly on the front for convenience, and the bottom cuffs are minimal, without any additional stretch built in.

rei co-op midweight bottoms long underwear review - the thick, 1.5" wide waistband is comfortable and holds well against...
The thick, 1.5" wide waistband is comfortable and holds well against the skin, without irritation.
Credit: Justin Simoni

Durability


The Midweight Bottoms are all but custom-made for the accident-prone, like our main tester who can't help but bump into trees and slip on ice. They are one of the burliest pairs we've tested, thanks to their midweight synthetic fabric and tight weave. Our harsh lab tests that usually leave most wool long underwear shredded resulted in only superficial damage to the REI Midweights.


In our real-world testing, we found no degradation to the comfortable four-way stretch, which hasn't lost its shape or elasticity. Tough, flatlock seams are found exclusively throughout the bottoms, and we noticed no premature wearing of these seams or of the fabric itself. The thick 1.5" waist strap has plenty of stretch and can take a fair amount of abuse. We would suggest following the manufacturer's recommendations of only drying on low, as there is elastane in the waistband and, if we were to guess, in the fabric itself.

rei co-op midweight bottoms long underwear review - durability of the rei midweight bottoms is excellent as the...
Durability of the REI Midweight Bottoms is excellent as the synthethic fabric resists abrasions. The snug fit and four way stretch of the fabric survived our repeated washings.
Credit: Justin Simoni

Drying Speed


The Midweight Bottoms fared decently here. The synthetic fabric has a tight weave, and the fabric weight itself is the thickest of any of the synthetics that we've tested, so the results we gathered track. Drying times were faster than the thickest wool and wool blends we've tested, but this is also to be expected, as wool usually holds onto moisture a little more than synthetics.


Cross-referencing these findings with what we've seen with warmth and breathability would suggest to us that the REI Midweight Bottoms are best for colder outings, where you don't run into the issue of overheating and over-perspiring. Putting these to work while ski touring would be an excellent use case. Once at the hut, hang them up to dry near the fire, and they'll be perfectly dry for the next morning's laps up the adjacent hill. Unfortunately, these bottoms don't come with any odor control/antimicrobial technology, so there's a chance that they will start smelling a little ripe after a few uses between washes. We personally didn't experience anything overly offensive, which we're grateful for avoiding.

rei co-op midweight bottoms long underwear review - drying speeds for synthetics like the rei co-op midweight bottoms...
Drying speeds for synthetics like the REI Co-op Midweight Bottoms are faster than their woolen brethren.
Credit: Justin Simoni

Layering Ability


The REI Midweight Bottoms are built to be social butterflies at the layering party. The smooth fabric works well when layering up with mid and top layers, as the material won't catch on other scratchier apparel. In our real-world tests, we paired the Midweight Bottoms with running tights, hiking pants, down pants, and our bedtime flannels without a problem. These bottoms are designed to be worn underneath another layer, as the presence of a front fly will attest. Not being an aggressive, athletically tight fit, you can wear a layer underneath the REI Midweight if you so desire — we regularly wore a pair of running shorts ourselves. That said, we would suggest them as a next-to-skin layer for most applications.


The fabric's four-way stretch also prevents the bottoms from bunching up in awkward and hard-to-reach ways, which is important for a mid-layer. Minimal cuffs at the ankle do their job in keeping the legs from riding up, and the midweight fabric didn't feel too bunchy when paired with a thick sock or clunky hiking boots. Stitching and seams are fairly minimal throughout these bottoms, and none are located in any problematic areas, like the crotch, which is gusseted to avoid such issues.

rei co-op midweight bottoms long underwear review - the rei midweight bottoms are snug, but not athletically slim and...
The REI Midweight Bottoms are snug, but not athletically slim and tight. The inseam is reasonably long, ending just at the top of the ankles for our main tester.
Credit: Justin Simoni

Should You Buy the REI Midweight Base Layer Bottoms?


If you want the best midweight synthetic long underwear that we've seen, this is it. The excellent price is just an added bonus — chances are that we'd give you the same recommendation if these leggings were twice the price. Their only real weakness — if you can even call it that, is their absolute warmth, given their weight. A wool or wool blend base layer would be just a little bit warmer. Unless you're counting grams for your next FKT attempt, these bottoms will keep you warm all season — and because they're so durable, for many seasons to come after that.

rei co-op midweight bottoms long underwear review - we literally put the rei midweight bottoms onto the highest pedestal...
We literally put the REI Midweight Bottoms onto the highest pedestal we could find.
Credit: Justin Simoni

What Other Long Underwear Should You Consider?


For a comparable synthetic, check out the Patagonia Capilene Midweight Bottoms — they better the REI Midweight in that they have an odor control treatment in the fabric, though they're not quite as warm. For a wool pair at a similar price, look to the Meriwool Merino 250 Bottom; they'll be a lot warmer but will need some more care when you wash them. For a more performant bottom that's still a great deal, check out both the Icebreaker Merino 200 Oasis Bottoms. They have a similar pattern, including the gusseted crotch, are almost as stretchy, and will also be a little bit lighter.

Justin Simoni
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