What to Wear Under a Sweater

Start with the neckline, not the shirt

Most advice about what to wear under a sweater starts with the occasion. That is backwards. The sweater’s opening is a fixed shape, and it either has room for a collar or it does not.

We make the first three. We do not make a turtleneck, and it is listed here only so the table is complete.

The funnel neck in that table is the quarter zip’s collar — a standing band that does not fold down — and it is the one shape where the underlayer decision is made for you. What it takes and what it fights is set out on Funnel Neck Sweaters for Men.

A t-shirt: the default, and why

A thin t-shirt under a sweater is right most days, and the reason is maintenance more than warmth. Skin oils and sweat go into whatever touches the skin. If that is the sweater, the sweater gets washed; if it is a tee, the tee does. On a garment that has to be hand washed at a maximum of 30 °C and dried flat, that is the difference between a five-minute job every couple of weeks and one every few wears.

Three things to get right:

• Match the neckline. Crew tee under a crew sweater, V tee under a V. A mismatched tee is the single most visible layering error, and it is visible in every photograph.
• Match or lighten the colour. Under pale knits — Sand, Sandstone, Oat, Sky Blue — a dark tee reads through as a shadow across the chest. Under Charcoal Black or Graphite nothing shows through at all.
• Keep the sleeve short. A long-sleeve tee under a knit sleeve bunches at the elbow and shortens the reach of the sweater cuff.

A collared shirt: which collars survive

A shirt under a sweater is the business-casual default, and the failure is almost always the collar rather than the shirt. A knit collar has weight. It presses down on whatever is inside it.

• Button-down collar. The most reliable under a crew neck, because the buttons stop the points from wandering out over the ribbing.
• Spread or semi-spread with stays in. Structure is what holds it up. Take the stays out and it collapses.
• Soft, unstructured, washed collars. These look excellent alone and terrible under a sweater. By mid-morning one point is under the knit and one is over it.

Under a V-neck, the shirt is doing real work: the V frames the collar and the top of the placket, and this is the only common sweater neckline that leaves room for a tie knot. If the collar-and-tie case is what brought you here, the detail is on Wearing a Sweater Under a Blazer (and Suit).

Under a crew neck, you have a choice: collar out, which reads traditional, or collar tucked in, which reads cleaner and is what most people actually do now. Both are fine. What is not fine is half of each.

A polo, and the case for nothing at all

A polo splits the difference — a collar with no tie and no cuffs to manage. Under a crew neck it gives you a collar without the formality of a dress shirt; under a V-neck it fills the opening softly rather than framing it sharply. A knitted polo collar is less likely to collapse than a soft woven one.

And nothing at all is a real option, provided the sweater is fine enough. That is a question about fibre diameter: prickle comes from fibre ends stiff enough to press back against skin, and below roughly 30 micron they bend instead. A wool coarse enough to approach that threshold will itch some people. Cashmere at 12–16 micron is nowhere near it. The cost of bare skin is laundry, which is the next section.

Warm weather flips what the underlayer is for. In an over-cooled office in July a thin tee under the knit is doing sweat management rather than insulation, and that changes the fabric you want against the skin — the seasonal version of this argument is on Can You Wear Cashmere in Summer?

The measurements that make layering work

Layering fails on length far more often than on width. Two numbers decide it, and both are measurable on garments you already own with a tape and a flat table.

• Sleeve. Ours run 60–68 cm from the shoulder seam. Measure your shirt the same way. If the shirt is longer, it will bunch at the elbow and push out of the cuff — which is fine if you want cuff showing, and a mess if you do not.
• Body. Ours run 64–73 cm. A shirt tail longer than that will hang below the hem unless it is tucked, and an untucked shirt under an untucked sweater is two hems fighting.
• Chest. Flat measurements of 48–56 cm, so double them for the circumference. If you are between sizes and you plan to wear a shirt under it, take the larger — a knit stretched over a woven shirt pulls at the placket and reads tight in photographs before it feels tight on you.

Measurements are the garment laid flat, in centimetres, and are the same across all colourways. Full detail on the Men's Cashmere Sweater Size Guide & Fit.

What to wear under a cashmere sweater

Everything above still applies, and two things change. Cashmere is finer and more expensive than most knitwear, and both facts push the answer in the same direction: thin, smooth, flat-seamed, or nothing.

Friction is what makes cashmere pill. Short surface fibres work loose under rubbing and tangle into balls. A rough layer underneath, a stiff overlocked seam, a printed transfer with a hard edge — each of those rubs the same square centimetre all day and produces pills exactly there. A smooth cotton or fine merino tee with flat seams does not. This is a bigger factor than anything you wear over the sweater, because the inside face is in constant contact. The mechanism is set out in full on Does Cashmere Pill?

Bare skin is comfortable and costs you laundry. At 12–16 micron there is no prickle, and cashmere against skin is genuinely one of the reasons to own it. But the fibre takes up oils and sweat, and the only correct wash is by hand at a maximum of 30 °C, reshaped damp and dried flat. Most people who wear cashmere directly end up washing it two or three times as often as people who put a tee underneath. Decide which you would rather do.

Watch static. Dry indoor air plus a synthetic layer under cashmere makes the knit cling to the layer beneath and lift away from the body. A natural-fibre layer underneath mostly solves it.

What not to put under a sweater

• A hoodie. The hood has to go somewhere and the somewhere is the back of your neck, under the collar.
• Anything with a chest print or a hard transfer. It shows as a raised patch through a fine knit and it abrades the inside face.
• A second sweater. Two knits fight each other at the shoulder and neither drapes. If you need more warmth, add a layer over, not under.
• A shirt with a long, unstructured collar. Covered above; it is the most common failure by a distance.
• Anything damp. Wet fibre against a knit stretches it, and cashmere holds moisture longer than you expect.

If the reason you are layering is that a jacket is going over the top, the constraints change again — jacket sleeves and shoulders set their own limits. Those are on How to Wear a Sport Coat with a Sweater. Otherwise, start from the neckline and work outwards. If a tee is your default layer, the sweater to put over it is the Men's Crew Neck Cashmere Sweater; if it is a collared shirt, the Men's V-Neck Cashmere Sweater. Both are $155, S–2XL, and sit alongside the quarter zip on Men's Cashmere Sweaters.