Thermal underwear

Men's thermal underwear: how to choose and buy it well

Updated 20 October 2026

Cotton does not keep you warm when it's wet

The main rule of thermal underwear: it must carry sweat away from your body, not soak it up. Cotton absorbs moisture and stays wet for a long time, so you freeze quickly in it in the cold. For active use choose synthetics or wool.

• Polyester and polypropylene – move moisture away and dry quickly; good for activity such as skiing, running or long treks;
• Merino wool – keeps you warm even when damp and stays fresh longer, but costs more and needs gentle washing;
• Fleece layers – a second layer for severe cold;
• Blends – a compromise between price and comfort.

Layer weight and temperature

Thin underwear suits moderate cold and active sports, medium weight is a good all-rounder for winter, and thick is meant for severe cold and low activity, such as waiting at a high-altitude camp or a night in the hills. How comfortable you feel at a given temperature depends on the wind, the clothes over it and how much you move, so mention the situation and not only the degrees.

What to put in your request

• What exactly – a set with top and bottoms, only a top, long johns, leggings;
• Purpose – trekking in the hills, snow sports, running, outdoor work, daily wear;
• Temperature – how low it must go, or the warmth level: light, medium, thick;
• Material – merino, polypropylene, polyester, fleece;
• Size – S/M/L or a number, your height and chest measurement;
• Brand – one you like, or any;
• Delivery city and budget – for example, up to ₱2,300 per set.

Example: “I need a thermal set (top and bottoms) for a winter trek in the mountains, down to −10 °C, polypropylene, size XL, height 185 cm. Courier delivery to Quezon City, budget up to ₱2,300 per set.”

How to compare offers

Compare the fabric content, the thickness and the warmth level: sets for different temperatures cost different amounts, and you should compare similar ones. Check for flat seams (they don't rub under a backpack or gear) and make sure the waistband does not cut in. Ask about the size chart and exchanges, because thermal underwear should fit snugly but not squeeze.

On BlaBlaPrice you describe what you need once, and clothing sellers send offers and compete on terms. The offer that gives the best value is shown first, with reviews of the seller next to it. Contacts stay hidden until you choose a seller. Details are on the “How it works” page.

Common mistakes

People buy “warm” underwear made of cotton and end up sweating. They buy thick underwear for active movement and overheat. They pick too big a size, so there is air between the body and the fabric, and air does not keep you warm. They wash wool in hot water, and it shrinks.

See also socks (thermal socks complete the set), briefs and swim trunks.