8 Best Thermal Pants of 2026

The baleaf joggers are the only pair here that read as outdoor pants first and thermal underwear second. The drawstring waist, tapered leg, and water-resistant shell make them look at home on a trail, while the fleece lining does the quiet work underneath.

The 25-, 28-, and 30-inch inseam options are the reason we can recommend them to more than one body type; that is rare in this category, where a single length often decides the fit. The shell sheds light rain and road spray, and the fleece lining adds warmth without the snow-pant bulk. We wore them on cold-weather walks and under a shell on a damp hike, and they stayed comfortable rather than clammy.

For hikers who want one pair that can handle a chilly trail and a casual coffee stop, this is our pick. The inseam is the main thing to check: taller wearers may find even the 30-inch option short. If you are mostly layering under rain pants, a simpler base layer is cheaper; if you want a standalone winter hiking pant, these earn the space. The drawstring waist is the detail that makes them feel secure on a climb.

The Carhartt Force pants feel like a piece of workwear that happens to be a base layer. The waffle knit has a dry, substantial hand, the waistband is built to stay put under jeans, and the midweight fabric is clearly aimed at people who spend the day outside rather than dash between cars.

For cold-weather work and serious layering, this is the pair we trust most in the men’s group. The fabric traps warmth without the clammy feel of a cheap cotton long john, and it breathes enough that you are not soaked after moving around. We wore them under work pants on cold mornings and under a shell on a windy hike, and they kept their shape.

The fit is the sticking point. The waist runs large on some builds and tight on others, so the size chart matters more than brand loyalty. The price is also at the top of the midrange, which makes the fit gamble harder to accept. If you know your Carhartt size and need a work layer, the extra cost is easier to justify; if you are between sizes, look elsewhere.

If you want a softer, lighter base layer for hiking, Merino.tech is the better choice; if you want maximum warmth for a workday in the cold, Carhartt’s extra substance is worth it. The waffle texture also keeps the fabric from clinging to outer pants, which is a small thing that makes a long day easier.

A 100% merino base layer is a different proposition from a fleece legging: the point is not maximum loft but staying warm, dry, and socially acceptable after a long day on the trail. The Merino.tech pants are light, thin, and soft enough to forget you are wearing wool.

The wool regulates temperature well. We wore them under hiking pants on chilly mornings and under jeans for outdoor work; they took the edge off without the clammy overheat we get from heavier synthetic base layers. Merino’s real advantage is odor control on multi-day trips, and these are the pair we pack when laundry is not an option.

The fit is true to size for most builds, with enough length to stay tucked. The fabric needs gentler handling than a synthetic base layer, so treat it like wool rather than workwear.

For hikers who prioritize breathability and odor resistance over bombproof construction, these are the best merino pick here. They cost more than the synthetic options, but the comfort on a multi-day trip is hard to match. If you want a base layer for rough work, Carhartt is the sturdier choice.

Under Armour’s ColdGear leggings are the closest thing here to a pair of winter running tights. The compression fit is snug from waist to ankle, the fabric has a smooth, cool-to-the-touch face, and the cut is clearly made for movement rather than lounging.

For high-output cold-weather days, this is the pair we choose: the compression supports the legs, the warmth is enough for running and fast hiking, and the fabric holds its shape after washing. It is firm enough to feel supportive without restricting your stride. The sizing is the catch—these run very small, and the fit is unforgiving if you are between sizes. Size up and they are excellent; ignore the chart and you will be sending them back.

The value is in movement, where the compression and breathability keep you from overheating. If you want a lounging legging, IUGA is the better fit; if you want a training layer for cold runs, this is the one.

The Fruit of the Loom waffle bottoms are the least expensive way into this list, and they look the part: a traditional waffle knit, a simple elastic waist, and a cut that is meant to disappear under jeans.

The waffle texture traps warmth well for the price, and the cotton-poly blend feels soft against the skin rather than scratchy. We wore them under jeans on cold days and under rain pants for a wet walk; they kept the chill off and never felt bulky. The longer leg is a bonus if you are tall or like to tuck them into boots.

For a cheap base layer that does the basic job, these are our budget pick. The sizing is the main gamble—the waist runs large and the legs loose on a lot of builds, so check the chart and consider sizing down. If you want a pair for occasional cold snaps or sleeping in a cold room, they are a smart buy; if you need a daily work layer, spend more. They are also the pair we are least worried about losing, which counts for something on a camping trip.

The first thing we noticed about the Heathyoga leggings is how well they stay put. The wide waistband does not roll, the fleece is soft rather than stiff, and the side pockets hold a phone without dragging the leggings down. For everyday winter wear, that combination is hard to beat.

They are not as thick as the IUGA pair, which makes them easier to wear indoors or under a dress, but they are still warm enough for cold commutes and morning walks. The fit is the thing to watch: the waistband runs snug on some builds. If you want a softer, less bulky legging for daily wear, these are a strong alternative; if you want maximum loft for deep cold, go thicker. The fleece lining is also smooth enough that it does not grab tights or jeans layered over it.

The outside has a smooth, matte finish that reads more like an everyday legging than athletic gear, so they work with a sweater or a rain shell. They are not a hiking-first pant; the fleece is too soft for serious abrasion. For a cold-weather errand run or a day at home, they are easy to live in.

The CAMPSNAIL leggings are the warmest-feeling pair here. The fleece is thick, almost blanket-like against the skin, and the outside has enough substance that you can wear them as pants rather than only as a hidden layer.

That thickness is the point. On a cold morning walk, they cut the wind and keep the legs warm without the stiffness of a snow pant. The fabric is stretchy enough to move in, and the high waist stays up rather than rolling down. We wore them for errands and a cold-weather camp morning, and they were the pair we reached for when the temperature dropped.

The trade-off is length and warmth. The legs run short on taller wearers, and they are too warm for active hiking or a warm car; these are for standing around, walking, and deep cold. If you are tall or want a pair for fast movement, look elsewhere; if you are shorter and want maximum loft for low-output days, these fit the job.

For deep cold and low-output days, these are the best thick fleece pick here. They are not the pair for a fast hike or a mild winter day—the IUGA is more versatile—but when the forecast is brutal, the extra loft earns its place. The high waist and thick band also mean they stay put when you are layered up in a bulky jacket.