13 Best Base Layers of 2026: Size Up and Stay Warm on Winter Trips

This women's thermal set uses heavyweight fleece to retain heat effectively, so you stay warm without the extra volume that makes layering awkward. The fleece lining is soft against the skin, and the construction holds up well to regular wear. Unlike lighter fleece sets, this one handles colder temperatures while still allowing easy movement under jeans or sweaters.

Designed for women who need a warm base layer for winter travel or daily outdoor activities, this set works well under clothing without adding noticeable bulk. However, the sizing can run small, especially in the bottoms – consulting the size chart and considering a size up is advisable. Those who prefer a lightweight or very snug compression fit will find this heavyweight option less suited to their needs.

The Amazon Essentials Waffle Knit Set brings a traditional thermal feel with the added convenience of multipack options. Unlike the fleece-lined sets common in this price range, the waffle knit prioritizes breathability and a classic look, making it a comfortable layer for daily winter wear.

This set suits buyers who need a reliable base layer for moderate cold — temperatures above freezing. The fabric is lighter than heavy-duty thermals, so it won't handle sub-zero conditions. The snug fit works well for layering, but ordering one size up helps avoid a tight squeeze, especially for taller frames.

Unlike thicker men's thermals built for standalone insulation, this set prioritizes a smooth, silky fleece that moves easily under fitted clothing. The lining retains enough heat for cold-weather layering without the bulk.

Best for women who want an affordable base layer that won't add bulk under jeans or sweaters. The fleece is intentionally thin, making it ideal for travel or daily wear rather than extreme cold. Note that the sizing runs small – ordering one size up is recommended for a comfortable fit.

The HeatGear compression shirt uses a moisture-wicking fabric that feels cool during high-intensity activity, setting it apart from budget compression options that prioritize light insulation over breathability. The snug fit provides muscle support for runners, gym-goers, and anyone layering under a jersey in moderate cold.

This shirt is best suited for athletes who need sweat management and muscle support rather than heavy insulation. The fit runs small: ordering one size up is recommended for comfortable range of motion. Seam durability has been inconsistent in some units, so inspecting the stitching after a few washes is worth doing.

At a budget-friendly price, these compression pants offer a combination of fit, comfort, and chafe protection that rivals more expensive base layers. The fabric moves with the body during runs, rides, or gym sessions without restriction, making them a practical alternative to premium compression gear.

These pants suit runners, cyclists, and gym-goers who need a lightweight base layer for mild to cool conditions. The compression is light, so they won’t replace a firm support garment, and the sizing runs small — those between sizes should order up. They are not intended for heavy insulation in extreme cold.

This 100% merino wool set delivers natural temperature regulation and breathability that synthetic base layers cannot match. The fabric wicks moisture effectively and stays comfortable across a wide range of activity levels, making it a strong choice for hiking or skiing in fluctuating conditions.

Ideal for travelers who value odor resistance over multiple days without washing and appreciate the soft, itch-free feel of fine merino. However, the delicate fibers are prone to developing holes after limited wear, especially under backpack straps or with frequent machine washing — a tradeoff that suits those who can handle gentle care but not backpackers needing abrasion resistance.

This set provides good warmth and a soft, non-itchy feel that's comfortable against the skin. The fleece lining adds insulation, though some units may lack it as advertised. Sizing runs small; plan to order at least one size up, possibly two. These tradeoffs mean it's not a top pick, but for those willing to size up, it's a warm and affordable option.

The SIMIYA thermal set offers a budget-friendly way to add warmth without stiffness. Its soft fleece lining feels gentle on skin and stretches with movement, ideal for casual wear or as a mid-layer. However, the fabric is thinner than many fleece-lined thermals, limiting its use to cool days rather than deep winter. Sizing inconsistency means some may need to size up or down depending on the garment.

This set delivers real fleece-lined warmth at a rock-bottom price. The fabric is noticeably thinner than typical thermals, so it's best as a light base layer rather than heavy-duty insulation. Sizing runs small enough that ordering at least one size up is necessary for a comfortable fit. That makes it a functional option for budget-conscious buyers who want basic cold-weather coverage without spending much.

This 5-pack of compression shirts delivers an exceptional per-shirt cost for women who need multiple base layers for gym wear or underscrubs. The sleeve length works well under uniforms and the color variety adds flexibility. However, sizing runs consistently small, so ordering up is necessary, and the fabric can feel rough against sensitive skin, with occasional moisture visibility under light layers.

The romision Thermal Set delivers a smooth, satin-like interior and good breathability, ideal for active use in cold weather. Its fleece lining provides warmth, but the shirt runs small — sizing up is necessary. While slightly pricier than the HEROBIKER set, it offers comparable warmth and softness, making it a secondary choice for those prioritizing feel over budget.

This thermal set stands out for its soft, silky fleece lining that feels comfortable against the skin and provides lightweight warmth suitable for skiing or everyday cold weather. The main drawback is that the set runs small, so ordering one size up is necessary for a relaxed fit. While it offers good value, similar options from Cuddl Duds and PISIQI earn higher satisfaction in warmth and fit, making this a solid alternative rather than a top choice.