A comfortable and lightweight merino layer that does an incredible job at regulating body temp, keeping you warm when the digits drop and breathing terrifically when your heart rate is pumping. The SmartWool Merino 150 Bottoms are a super versatile pair of bottoms that can be used all year long and will perform at the highest levels. Issuing awards for bottoms was tough because so many bottoms performed wonderfully. These were one of the pairs that we had a tough time not giving an award. A really nice fit with a simple and efficient seam design and super comfy waistband, these bottoms became a go-to partner in crime anytime we were heading out to play. The downside, as always, with merino, is we wish they were a little tougher. The bottoms that performed as well as these did in versatility, breathability, and comfort, were the Editors' Choice Award winner Outdoor Research Alpine Onset bottoms which offer slightly more warmth. Keep scrolling to read about this all-star bottom from SmartWool.
SmartWool Merino 150 Bottoms Review
Cons: Not very durable
Manufacturer: Smartwool
Our Verdict
Compare to Similar Products
 This Product
SmartWool Merino 150 Bottoms | |||||
| Awards |  |  | |||
| Price | $75.00 at Amazon | $61.73 at REI Compare at 2 sellers | $89.00 at Backcountry Compare at 2 sellers | $100.00 at REI Compare at 2 sellers | $79.50 at REI |
Overall Score  |
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| Star Rating | |||||
| Pros | Warm, lightweight, breathable, versatile, comfortable, great thermoregulation | Warm, lightweight, great breathability, versatile, quick to dry, anti-odor, great fit | Warm, super comfy, durable, great fit, versatile, don’t stretch out | Extremely warm, super cozy, terrific temp regulation, breathable | Comfy, warm, simple, breathable |
| Cons | Not very durable | Not super durable, not for super cold | Pricey | Stretches out, soggy crotch, slow to dry, expensive | Not very durable, tend to stretch |
| Bottom Line | A fantastic pair of lightweight merino bottoms that provide impressive warmth without being too hot, breathe extremely well and are very comfortable. | A go-to, do-it-all merino base layer that provides superb insulation, incredible breathability, and a dialed-in fit for high performance in any situation you can dream up. | An outstanding synthetic bottom that offers great warmth, extreme comfort, a stellar fit, and durability to last; built for cold conditions these cozy bottoms are perfect for everything from winter trail running to cold resort skiing. | An extremely warm and breathable pair of bottoms built to keep you warm in the coldest conditions but versatile enough to carry into seasons outside of winter. | A simple and comfortable merino option |
| Rating Categories | SmartWool Merino 150 Bottoms | Alpine Onset Bottoms | Arc'teryx Rho LT Bottoms | SmartWool Merino 250 Bottoms | Merino Midweight Bottoms |
| Warmth (30%) | |||||
| Breathability (30%) | |||||
| Comfort And Fit (30%) | |||||
| Durability (10%) | |||||
| Specs | SmartWool Merino... | Alpine Onset Bottoms | Arc'teryx Rho LT... | SmartWool Merino... | Merino Midweight... |
| Material | 87% Merino Wool, 13% Nylon Core | 83% merino wool, 12% nylon, 5% spandex | Torrent (84% polyester, 16% elastane) | 100% merino | Ultra-fine 200g merino wool |
| Weight (size S) | 4.94 oz | 4.80 oz | 5.57 oz | 7.55 oz | 5.93 oz |
| Fabric Weight | 150g | Not listed | Not listed | 250g | 200g |
| Fabric weights and other versions available | 150, 250 | Lightweight | Boot-cut | Lightweight, midweight | Midweight |
| Fly? | Yes | Yes | No | Yes | Yes |
| Dryer safe? | Yes | Yes | Yes | Yes | Yes |
Our Analysis and Test Results
A stellar lightweight merino base layer that holds true to SmartWool's reputation of being the masters of merino. Thoughtfully built with great warmth and breathability, these bottoms are an all-around champion for everything except bitter colds.
Performance Comparison
Warmth
For how thin these are, they are impressively warm. Merino has an incredible ability to provide insulation even with a thinner fabric. These do a great job of insulating when they are under a shell and able to hold onto heat. If you wear them with a thin, breathable pair of pants, they will be less warm which is why they are so versatile. Put them under an insulated pant for maximum warmth, a water-proof shell for medium warmth, and a light pair of breathable hiking pants for maximum breathability. We loved them for backcountry skiing when the temps weren't frigid and everything else that lives above ice cold. Backpacking, lounging, traveling, hiking, Alpine climbing - the pant does it all. A perfect weight for active endeavors in everything except arctic conditions. A slightly warmer pair of bottoms that perform as stellar in breathability and versatility are the Outdoor Research Alpine Onset bottoms.
Breathability
These excel at breathability and wicking away sweat. The inherent qualities of awesomeness that merino already has are increased by the thinner weight fabric. Take merino's ability to breathe, wick sweat, and dry quickly and multiply it and you have the SmartWool 150 pant. Skinning in warm conditions in the Rockies, these were the perfect layer, breathing and wicking away sweat on the uphill slogs, always keeping us dry but maintaining warmth when clouds rolled in and the temps dropped.
Comfort & Fit
A super comfortable pair of bottoms, we found they were good for wearing all day. They didn't stretch out as significantly as other merino layers like the SmartWool Merino 250 after heavy use. Maybe due to the fact that SmartWool wrapped a merino fiber around a nylon core for added durability and shape retention, no matter the reason we aren't complaining. Comfortable next to skin, they fit tight like a traditional base layer.
They have minimal flatlock seams that you don't even notice are there. A single inseam runs the length of the pant meeting up with the crotch. There is a tiny bit of crotch sag, but if you wear them at your bellybutton, they fit like a glove. The wide waistband is comfortable for all-day wear. The ankles are really tight and require some care pulling over your heal, or you could easily rip the thin merino fabric. Overall, great comfort and fit. At 6 ft and wearing a small (30in waist), they were a tad bit short exposing a little bit of ankle. If we could change anything, it is to reduce the minimal crotch sag and lengthen the legs a bit.
Durability
Durability, the Achilles heel of the praiseworthy warrior of base layers, merino wool. These bottoms are no exception, they just aren't that durable. SmartWool attempted to increase durability by wrapping the merino fabric around a nylon core which we think helps with shape retention and overall longevity but when it came down to our merciless abrasion test, we smoked a hole right through these bad boys.
Other merinos of a slightly thicker fabric weight like the REI Co-op Merino Bottoms bear the same scars from our abrasion test. As always with merino wool, don't climb granite chimneys in your merino chonies and don't put them in the dryer. If you follow these two easy rules, a merino base layer can last you for years of use.
Best Applications
These lightweight bottoms are created for high output activities in cool to cold weather. We suggest using them for backcountry skiing, trail running, walking your dog, reading a book in a log cabin, eating cereal, winter desert climbing, and backpacking. They are a wonderfully versatile weight that can dump heat and stay dry when you're at max output as well as insulate well in colder conditions. Anything outside of freeeeaking cold, these bottoms will do the job!
Value
At $75, they fall a little above the middle of the ground for pricing. We think with the quality of performance, they are well worth the price.
Conclusion
Our conclusion… these things rock. A great versatile layer made of comfortable lightweight merino wool that breathes exceptionally well and carries impressive warmth for how thin it is, we really enjoy these bottoms and think you will too!
— Roland Mott