The Smartwool Merino 150 Boxer Brief is an excellent choice and a classic pair of merino wool underwear. The fit is good, the material is soft and comfortable, and the construction is quality. The waistband is burly. At first, it may seem like overkill, but it also maintains its elasticity over time better than most models we have ever tested after over a year of use. The fabric also breathes surprisingly well for how "wooly" it feels. This has become our favorite pair for the backcountry. Between the bomber waistband, the high-quality fabric, and the comfortable form, the Smartwool Merino 150 deserves our Editors' Choice Award.
Smartwool Merino 150 Boxer Brief Review
Compare prices at 3 resellers Pros: Durable, soft, good odor control
Cons: Heavy, extra thick waistband
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Our Analysis and Test Results
The Smartwool Merino 150 is like a mid-nineties Toyota; it may not have tons of bells and whistles, but it is well built and will far outlast the competition if taken care of. The entirety of the design of these seems to be geared toward comfort and durability. While this may seem high end for a pair of underwear, this is a great pair for travel, backcountry, or daily use.
We thought that generally, the Smartwool Merino 150 was pretty comfortable as underwear goes. We liked the fit, not too baggy or tight, and a nice leg length so they don't chafe or bunch. There are seams in the middle of the crotch, but not right in the center, or in the front, so we didn't really notice them, which is good.
The fabric is a Core Spun merino wool, meaning the wool fibers have been wrapped around a nylon core to increase the durability. The fabric felt slightly less stretchy than the other wool underwear, but that could have been because of the burlier stitching. It also felt a bit "woolier," perhaps because of the thicker fibers. Otherwise, the fabric felt as soft as any merino normally does, as the Core Spun fibers still keep only wool touching your skin.
Initially, we didn't love the waistband. The outside is elastic, and the inside is lined with merino wool. It is twice as thick as any other pair we tested and wider than most at one and a half inches, but after months of regular active use, it has held up much better and remained stretchy and fitting. It can feel like a bit much when layering over it, but once it was on we didn't notice it really. Over time, we've noticed that the thicker waistband also seems to help with hip chafing from things like low backpack waistbelts or climbing harnesses, which is a very good thing.
Breathability is one of the things merino does surprisingly well, and the Smartwool boxer briefs are no exception. The wool breathes nicely and regulates temperatures well, never getting too hot or too cool, except around the big waistband. We did feel a bit sweatier at the band, but it doesn't move around, so we didn't get any salt rashes or anything, even in temperatures above 105 °F.
We also didn't notice any reduced breathability due to the nylon in the Core Spun fabric, or even any difference in feel. Overall, they're among the most breathable of any pair we've tested, as one would expect.
Again, this is a category where merino wool excels. The rough texture of the wool fibers and the natural lanolin (a waxy coating present in all wool) coating keeps the stink at bay, preventing microbes from latching on to the material. After running or cycling in them, they definitely smell used, but not out of the ordinary, and the smell reduced after airing them out for a bit.
This pair was on par for odor control with the rest of the wool skivvies, where they achieve a certain amount of odor, then plateau (synthetic fabrics seem to acquire stink until a weapons-grade smell emanates from them).
These are by far the burliest pair of skivvies out of all models we tested. The flatlock seams are tight and burly, even at the hem where other pairs go with lighter stitching. The waistband seems to have enough elastic for a decent wrist rocket. Even the printed logos showed no sign of wear. The Core woven fiber technology has also helped the fabric stay smooth and stretchy after months of use, and we haven't had any runs in the fabric so far. We think that in the long run the Smartwool Merino 150 will far outlast the competition. And for one tester, they have proven to do exactly that — after 1.5 years of use, they still look great with almost no sign of wear. A very rare feat.
Due to the thick waistband and extra seams, these were one of the slowest pairs to dry. They dry a little quicker than some others in the sun, likely because of the black color absorbing more sunshine, but they still dry slowly. Unlike synthetic fabric, wool absorbs water into the fiber itself, rather than just the spaces in between. Still, they're plenty thin enough to dry overnight for a fresh pair the next day.
They aren't the most expensive pair, but they're close. Merino wool and good craftsmanship come at a premium. Still, given their incredible durability and lack of stinkiness, we think they're worth it if you're willing to shell out for a good pair.
The Smartwool Merino 150 Boxer Briefs is a classic that stands the test of time. Initially, we were wary about how thick the waistband is, and it sometimes seems overkill for daily use, but we ended up really liking them for being active outside, even for days in a row. The soft wool and smartly places seams were really comfortable. We were impressed enough to award them the Editors' Choice Award. We think the high-quality construction, core woven fabric, and overbuilt waistband will keep you reaching for them again and again.
— Ethan Newman