Reviews You Can Rely On

How We Tested Base Layer for Women

Monday June 20, 2022

Boy howdy, have we been adventuring lately. This review keeps our seasons chock full of many pursuits, with hundreds of hours spent adventuring and working in each base layer. We have spent our winter days running through snow-laden trails and skiing up and down snowy slopes. From multi-pitch climbing to heights over 1,000 feet and hiking through the desert to trail running around high summits of the Cordillera Blanca in Peru, these base layer tops have seen all sorts of conditions. We rated each based on warmth, breathability, comfort, fit, layering ability, and durability.

base layer womens - taking a little afternoon jog with the patagonia capilene midweight...
Taking a little afternoon jog with the Patagonia Capilene Midweight Crew.
Credit: Amber King


Each product was worn as part of a layered system in frigid temperatures, including some that reached the double negatives in Northern Canada. Each was worn on its own to determine wicking ability and overall stand-alone warmth while running and hiking in the San Juan mountains.

Since each base layer comes in a varying levels of thickness, we identified which layer offered the most warmth, while taking into consideration the overall weight of the layer. Some layers provided a ton of warmth but also held onto moisture generated during rigorous activity and some of the lighter layers surprised us with the warmth offered by a thinner fabric. The layers that provided the maximum amount of warmth received the highest scores.

base layer womens - cold weather in northern canada and washington state had us testing...
Cold weather in Northern Canada and Washington State had us testing in temperatures that dipped into the double negatives. Here we test on a lift at Mt. Baker when temperatures hovered just around zero degrees Fahrenheit.
Credit: Jordan Erlenbach


We skinned uphill for hours, ran hundreds of miles on trails, and stood around in windy places. We wore each layer on its own and in a layered system to determine the best for breathability.

From synthetic to merino, our testers identified which base layers were able to trap heat generated during activity while also releasing any excess moisture. We took notes on which layer would function year-round or shine for just a season. Some of the lighter layers breathe so well they would not be suitable for a colder climate, however, some of the warmest layers wouldn't release moisture at all and eventually lose any available warmth. The layers that kept us warm and dry received the highest scores.

base layer womens - skinning, trail running, and hiking were all the different modes of...
Skinning, trail running, and hiking were all the different modes of testing for breathability in both a layered and unlayered system. Here the Icebreaker (that can't be seen) does well on this snowy day in the wet climates of Washington state.
Credit: Amber King

Comfort Fit

Using a wide diversity of testers, we looked at the fit of each top simply by trying it on and comparing the stretchiness as well as the length of both arms and torso. We also looked at style features, including zip neck vs. crew-collar designs and any other enhancing features such as thumb loops, stow-away pockets, or hoods.

For comfort, we simply noted how the layer initially felt against our skin. Then we took the layer to the hills either trail running or backcountry skiing so we could determine if the fabric remained comfortable during movement or felt itchy next to our skin. We also noted which tops our testers preferred day-to-day.

base layer womens - the smartwool merino 250 1/4 zip is a favorite for its excellent fit...
The Smartwool Merino 250 1/4 Zip is a favorite for its excellent fit and cozy materials. The cut is versatile, making it a great choice for a wide range of activities, whether you're lounging around town or skiing at the resort.
Credit: Amber King

Layering Ability

This test was fairly simple. We simply stacked layers over the top and underneath each shirt, noting which bunched in the arms, rode up, or simply stayed in place. We also noted which tops provided more room to put a layer underneath for warmer days of play.

While most base layers are easy to layer on top of, we found that some pesky and unnecessary seams can really detract from the overall comfort of the layer and often times the discomfort is amplified with another layer over top. The base layer that offered a smooth fabric with minimal seams received the highest score in this metric.

base layer womens - layering the hannah is a little harder than other synthetic...
Layering the Hannah is a little harder than other synthetic competitors because of its stickier face fabrics. That said, we enjoy the long arms that allow us to pull them through the mid layer.
Credit: Jordan Erlenbach


For this test, we beat the crap out of each piece. We wore each while bushwhacking in the woods, shimmying through tight slot canyons, and while climbing in the desert. We also washed each layer numerous times to test the overall construction.

After many hours of exposure to the elements, we noted each garment's fabric snags, wear and tear, pilling, shrinkage, and odor. The layers that held up to these rigorous tests while maintaining structure received the highest scores.

base layer womens - the construction of the arc'teryx rho lt is holding up in the desert...
The construction of the Arc'teryx Rho LT is holding up in the desert better than our favorite pair of jeans, sporting flat lock seams, fitted cuffs that hold the layer against your wrists, and an overall thicker material that lasts.
Credit: Toby Swimmer

Ad-free. Influence-free. Powered by Testing.

GearLab is founded on the principle of honest, objective, reviews. Our experts test thousands of products each year using thoughtful test plans that bring out key performance differences between competing products. And, to assure complete independence, we buy all the products we test ourselves. No cherry-picked units sent by manufacturers. No sponsored content. No ads. Just real, honest, side-by-side testing and comparison.

Learn More