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When temps drop, your first thought might be that you need to get a warmer jacket, but one of the easiest ways to boost the warmth of your winter kit is to simply add a great base layer. The best ones keep you warm and cozy while still letting your skin breathe.
The overall best base layer we tested is the Icebreaker Merino 200 Oasis Crewe. This 100% Merino wool top is super soft on the skin, has a great fit, and the low-profile crew neck makes it easy to layer under anything from a fleece to a sweater to a puffy.
For the budget-conscious shopper looking for a good value, check out the REI Co-op Midweight Base Layer Crew. The soft, stretchy fabric and durable construction will save you money compared to premium options.
We’ve purchased and tested dozens of the best base layers for women since 2015, and our current review features some of the most innovative options we’ve seen to date. From casual hangs around the campfire to adventures like sailing the high seas to scaling thousand-foot cliffs, skiing in the high mountains, and running ultra-distance miles, we put these layers through their paces to find the best.
Editor’s Note: Our women’s base layer review was updated on March 16, 2026, to include new models from Arc’teryx, Stio, and Ibex in addition to updated testing perspectives on current and previous award winners.
