Modal vs Merino Wool vs Cotton: Base Layer Fabrics Compared

Four fabric families, one job. The right choice depends less on which is "best" and much more on how often you will wash the garment and how cold you will actually be.

Updated October 2026 · 9 min read

Base layer fabric choices get presented as a ranking, with one material at the top. That framing is not very useful, because the ranking changes completely depending on whether you are walking a hill for four hours or sitting at a desk with the heating off.

What follows is a straight comparison of the four families worth knowing: merino wool, modal and viscose, cotton, and nylon compression. It covers how each behaves when damp, how it feels over a full day, what it costs you in care, and what it costs you in money.

The Four Base Layer Fabrics at a Glance

Before the detail, here is the whole comparison in one table. If you only read one section, read this one.

	Merino wool	Modal / viscose	Cotton	Nylon compression
Warmth when damp	Excellent	Good	Poor	Good
Next-to-skin comfort	Very good at fine micron counts	Excellent, lowest friction	Good when dry	Good, slightly compressive
Itch risk	Depends on micron count	None	None	Minimal
Odour over 2–3 days	Excellent	Good	Poor	Good
Dries fastest	Slow	Fast	Very slow	Fastest
Care burden	High: cool wash, air dry	Low: normal wash	Low: normal wash	Low: normal wash
Price band	Highest	Mid	Lowest	Mid–high
Best suited to	Multi-day cold trips	Daily winter wear	Static cold, budget	High-output activity

Merino wins when you are away for days. Everything else wins when you are at home every night and washing it.

Merino Wool: The Warm-When-Damp Champion

Merino's genuine technical advantage is moisture, and nothing else in this list matches it. Wool fibres can absorb close to a third of their dry weight in water while still feeling dry to the touch, holding that moisture inside the fibre rather than on the surface.

Surface moisture evaporates and cools you. Moisture held inside the fibre does not. That single mechanism is why merino became the default for expedition base layers and why it still dominates among people who spend real hours in genuinely cold conditions.

The variable worth understanding is micron count, which is the diameter of the fibre. Finer fibres bend more easily and sit flatter against the skin, so they feel soft. Coarser fibres poke, particularly when skin is dry or the garment has been worn for days. Under roughly 19.5 microns is generally comfortable on bare skin; above 22 microns, expect some prickle at the neck and cuff seams where fabric folds and presses.

The reason merino loses people is rarely the wearing experience. It is the laundering one.

Modal and Viscose: The Smooth Everyday Answer

Modal and viscose are regenerated cellulose fibres made from wood pulp. Their reputation comes from the hand: nearly frictionless against the skin, and unlike wool there is no micron variable and no itch to manage.

On moisture they sit in a reasonable middle. They wick adequately in a fabric blend and dry quickly compared with cotton, but they are not engineered to keep you warm while saturated. If you are going to be properly wet and stay that way, this is not the fabric for it.

Where they win decisively is maintenance. Modal survives a normal warm wash and a tumble dry without losing shape or softness, needs no special detergent, and does not need to be dried flat. If your laundry routine does not allow for careful garment care, that advantage is worth more than a technical edge you will never use.

Cotton: Cheapest, Familiar, and Wrong for Activity

Cotton is the traditional choice and the least expensive by a wide margin. It is perfectly acceptable for static cold, where you are not generating much sweat and the goal is simply not to be cold.

It is a poor base layer for anything active, for a specific reason: it absorbs moisture into the fibre, holds it against your skin, and takes a long time to dry. It also holds odour longer than any synthetic or wool option. Once you have worked in wet cotton for a few hours, it is difficult to go back to a wicking fabric.

Cotton's real advantage is price. If budget is the deciding factor and the use is static cold, there is nothing wrong with it.

Nylon Compression: Built for Movement

Compression garments in nylon are a different category from the other three, because they are designed for the skin layer during activity rather than for warmth on their own. They wick quickly, dry fastest, and apply steady pressure across the body.

That pressure reduces the vibration and shifting that causes chafing during repetitive movement, which is why they are common for running, cycling and court sports. As a standalone warm layer they are thin, so they need a mid layer and shell above them.

The trade-off is that they are less versatile. A compression piece is close to useless for standing around outdoors in January on its own.

How Each Base Layer Fabric Behaves When You Sweat

This is the single most important section in the comparison, because it is the situation that actually decides whether you are warm or cold at the end of a day.

Your body produces moisture constantly and considerably more once you move. What happens to that moisture is what matters. A base layer that pulls it away from your skin and passes it outward keeps your skin surface dry, and dry skin loses heat slowly. A wet skin surface loses heat quickly, because water conducts heat away from you far better than still air does.

Ranked on wet performance: merino first, then nylon and modal roughly level, then cotton last by a wide margin.

The practical implication is that the fabric question changes with the activity. For a static day in the cold, cotton is fine and merino's advantage is largely theoretical. For a day involving movement, cotton will cost you warmth, and merino's advantage becomes real money.

Cost Per Season: The Calculation People Skip

Merino costs more per garment. The more useful question is cost per wear, which depends on two things: how long the garment lasts, and whether you keep wearing it.

On price per wear, merino can win comfortably. A fine merino garment that lasts five winters across many wear cycles can undercut a cheaper garment replaced every second year.

On likelihood of continued use, the cheaper fabrics often win, because a garment that gets worn is worth more than one sitting in a drawer unwashed. A merino piece that feels like too much trouble to care for is worth nothing, however good the fibre.

There is also a middle path worth considering: merino-blend garments rather than 100 percent merino. Blends improve durability and reduce price while keeping a good share of the moisture benefit.

Which Fabric Should You Choose?

Here is the short version, then the reasoning.

Choose merino if you will wear the same base layer for multiple days without washing, you are doing high-output activity in cold conditions, you are buying a finer micron count for next-to-skin wear, or you already prefer wool and know how to wash it.

Choose modal or viscose if you wear a fresh base layer every day, you are commuting or working indoors in a cold building, you want the lowest-friction feel against sensitive skin, or you want a garment you can machine wash without thinking about it.

Choose cotton if budget is the primary constraint and your use is static cold rather than activity.

Choose nylon compression if the base layer is for running, cycling, gym work or any repetitive movement where chafing and fast drying matter most.

Consider a blend if you sit somewhere in between. A merino-modal blend gives up a small amount of wet warmth and gets back durability and easier care.

Modal vs Merino vs Cotton: FAQ

Is modal warmer than cotton?

Yes, in anything involving activity. Modal moves moisture away from the skin and dries faster, while cotton absorbs and holds it. In purely static cold the gap narrows to almost nothing.

Is merino warmer than modal?

When both are dry the difference is small and construction matters more than fibre. When damp, merino is clearly warmer. For everyday dry conditions modal is the more comfortable choice at a lower price.

Can I wash merino in a normal machine?

Yes, on a cool setting or a wool cycle with wool-safe detergent. The thing to avoid is tumble drying on heat, which does the real damage to the loft. Air drying flat is the safe option.

Does modal shrink?

Modal is generally very shrink resistant, especially in a cotton-modal blend. Follow the care label and avoid prolonged high heat, which affects any cellulose fibre.

Is it worth paying more for merino if I only wear it at weekends?

Probably not. The wet-warmth advantage matters when you are away for hours without access to a washing machine. If you are home every night, a good modal garment will serve you better for less money.

What about wool sensitivity or a wool allergy?

Then modal or cotton is the sensible answer and there is no real trade-off to think about. Merino's only meaningful advantage over modal is performance when damp, and that is irrelevant to you.

Still choosing between garments rather than fabrics? Read Long Johns vs Thermal Underwear: Which Do You Actually Need? next.