Under Armour Mens Base 4.0 Leggings for Extreme Cold - Warm Baselayer

In this review of the Under Armour Mens Base 4.0 Leggings, the bottom line is simple: these are a purpose-built cold weather baselayer for men who need maximum insulation without bulk. Designed as Under Armour's warmest ColdGear offering, the Base 4.0 locks in body heat with a soft, brushed grid interior that traps air and manages your microclimate. The reviewer found them best for low-activity winter pursuits where retaining warmth matters most, and noted the fabric also wicks sweat to keep dampness from compromising insulation.

Key Features

• Extreme warmth: The brushed grid interior traps air against the skin to hold heat in very cold conditions without adding bulk.
• Moisture management: Material wicks sweat and dries quickly so the leggings stay comfortable during intermittent exertion.
• Range of motion: 4-way stretch construction moves naturally with the body for better comfort under additional layers.
• Practical fit: Performance elastic waistband and working fly provide everyday wearability as long underwear or casual base layers.
• Built for cold: Specifically designed for snow and subzero use, making them suitable for winter runs, hunting, or layered outdoor work.

Who It's For

These leggings are aimed at men who spend time outdoors in very cold weather or who need a high-performance baselayer for winter training; think low-activity pursuits like hiking in snow, stand hunting, or commuting in subzero temps. The emphasis on heat retention and a brushed grid interior makes them especially useful when warmth is the top priority.

Shoppers who want lightweight activewear for high-intensity workouts or who require pockets should look elsewhere, since these are optimized for insulation rather than breathability at high output and they do not include pockets.

Pros & Cons

Pros

• Exceptional thermal performance from the soft, brushed grid interior for cold conditions.
• Quick-drying, sweat-wicking fabric helps prevent damp chill during activity.
• 4-way stretch and an elastic waistband deliver a comfortable, mobile fit under layers.
• Working fly adds everyday practicality compared with some baselayers.

Cons

• Fit is mixed for some customers-while snug for heat retention, the cut can feel awkward for certain body shapes.
• No pockets, limiting usefulness when worn alone or for quick storage needs.

Specifications

Brand	Under Armour
Model	Base 4.0 Extreme Baselayer
Inseam	30.5 in
Construction	4-way stretch fabric with brushed grid interior
Waist	Performance elastic waistband with working fly
Pockets	None
Performance tech	Sweat-wicking, quick-dry, UA Scent Control Technology

Our Verdict

The Under Armour Mens Base 4.0 Leggings are an excellent choice for men who prioritize warmth in extreme cold and want a high-performance baselayer that retains heat without bulk. They pair strong insulation with moisture management and stretch, making them good value for cold-weather activities; buyers seeking a lighter, more breathable training layer or storage pockets should consider alternatives.

Frequently Asked Questions

Are these suitable for running in winter?
Yes for low- to moderate-intensity cold runs; they excel at heat retention but may feel too warm or restrictive for very high-intensity training.

Do they have pockets or extra storage?
No, these leggings do not include pockets and are intended primarily as an insulating base layer.

How long is the inseam?
The inseam is 30.5 in, which fits most standard lengths under outer layers.