Business casual is a strange brief. Smart, but not a suit. Relaxed, but not the weekend. The shoes are loafers, brogues or clean leather sneakers; the trousers are chinos, wool flannels or a good pair of dark jeans. And somewhere between the two sits the sock, which most people pick in a hurry and regret by three in the afternoon.

The right office sock does two things at once. It looks considered when you cross your legs in a meeting, and it stays comfortable through eight hours of sitting, standing, walking to lunch and back. Here is how we think about it, and the pairs we reach for ourselves.

What makes a sock business casual

Height. Crew, every time. A crew sock sits mid-calf, so no skin shows when you sit down and the trouser rides up. Ankle socks belong to summer and sneakers; no show socks belong to loafers without socks at all. For the office, mid-calf is the rule.

Colour. The sock should relate to something: the trouser, the shoe, or one small accent elsewhere. Navy with navy chinos is the safest answer in the world. A soft grey melange with charcoal flannels is the second. A quiet stripe or a two-tone block is where it gets interesting, as long as the palette stays calm.

Material. Comfort over a long day comes down to the yarn. Combed cotton breathes, holds its shape and does not get clammy under a desk. In winter, a cashmere and merino blend adds warmth without bulk. A sock that is mostly polyester will look fine at nine and feel wrong by noon.

Everything below is knitted from the same base: a soft cotton blend (80% cotton, 19% polyamide, 1% elastane) on vintage machines at a family-owned factory near Braga, in northern Portugal, with a hand-linked toe so there is no seam to feel inside a leather shoe. The cashmere socks are a cashmere and merino wool blend, made in the same region.

1. Plain ribbed crew socks: the foundation

If your office leans more business than casual, start here. A plain ribbed crew sock in navy, black, khaki or off white is the closest thing to a uniform we make. The rib gives the sock a little structure so it sits cleanly against the calf, and the slub cotton has a subtle texture that reads as considered rather than corporate.

Navy goes with everything from chinos to grey wool. Black is the answer for black shoes and dark denim. Khaki and cumin are for anyone who wears brown shoes and wants the sock to disappear into the trouser. Off white looks sharp with cream or stone chinos and a loafer in summer.

Men Crew Socks, Navy€25 Men Crew Socks, Black€25 Men Crew Socks, Khaki€25 Men Crew Socks, Cumin€25 Women Crew Socks, Navy€25 Women Crew Socks, Black€25 Women Crew Socks, Off Purple€25

Shop men's plain crew socks and women's plain crew socks.

2. Melange socks: texture without pattern

Melange is the sock for people who find plain a little flat but do not want a pattern. The yarn is spun from two or three shades at once, so the sock has depth and a slightly heathered look, like a good tweed. It also hides a long day better than a flat colour: creases and wear simply do not show.

Light grey melange with charcoal or navy trousers is the classic office pairing. Brown melange is the one for tan brogues and camel chinos. Flamé blue sits somewhere between navy and denim and goes with almost everything a wardrobe contains.

Men Melange Socks, Light Grey€25 Men Melange Socks, Brown€25 Men Melange Socks, Acid Blue€25 Women Melange Socks, Light Grey€25 Women Melange Socks, Flamé Blue€25 Women Melange Socks, Black€25

Shop men's melange socks and women's melange socks.

3. Quiet stripes and colour block: a little personality

A business casual office is exactly where a sock is allowed to say something, as long as it says it quietly. The trick is to keep the palette inside the outfit: a black and ecru stripe with black loafers and a cream shirt, a blue and rust stripe with navy chinos and tan shoes, a two-tone colour block where one of the tones matches the trouser.

Our striped crew socks carry a few fine stripes on a plain ground rather than a full-leg pattern, so they read as detail rather than statement. The melange block socks split the sock into two heathered tones, which looks more like a design decision than a novelty sock when the trouser leg lifts.

For a Friday, or an office where sneakers are fine, our 5 Stripes socks go a step further: five bands of colour at the cuff on an ecru base. Pick a combination where one stripe matches something you are already wearing and it looks intentional.

Men Striped Crew, Black / Ecru€25 Men Striped Crew, Blue / Rust€25 Men Melange Block, Black / Ecru€25 Men Melange Block, Light Grey / Bright Blue€25 Women Striped Crew, Black / Ecru€25 Women Striped Crew, Ecru / Blue€25 Women Melange Block, Black / Blue€25 Women Melange Block, Light Grey / Ecru€25

Shop men's striped crew socks, women's striped crew socks, men's melange block socks and women's melange block socks.

4. Cashmere socks: the winter upgrade

From November to March, an office is a sequence of temperature changes: a cold platform, a hot train, a draughty lobby, an over-heated meeting room. Cotton handles most of it. A cashmere and merino blend handles all of it, because wool regulates heat and moisture rather than simply trapping warmth. Your feet stay dry in the warm room and warm on the walk back.

Our cashmere socks are a crew height with a fine rib, in the same quiet colours as the cotton range: navy, light grey, black, khaki, ecru, plus a few stripes. They are thin enough for a leather shoe, which is not true of most wool socks, and they are the pair people tend to buy one of and then come back for three more.

Men Cashmere Crew, Navy€35 Men Cashmere Crew, Light Grey€35 Men Cashmere Striped, Grey / Strong Blue€35 Women Cashmere Crew, Navy€35 Women Cashmere Crew, Light Grey€35 Women Cashmere Striped, Strong Blue / Navy€35

Shop men's cashmere socks and women's cashmere socks.

Which sock with which shoe

A simple rule: match the sock to the trouser for a quiet look, match it to the shoe for a slightly sharper one, and only let it contrast with both on purpose.

The details that keep them comfortable at five o'clock

A hand-linked toe. The toe seam is closed flat by hand, so there is no ridge pressing against the inside of a leather shoe. It is the single biggest difference between a sock that feels fine at nine and one that still feels fine at five.

A cuff that holds without squeezing. The ribbed top keeps the sock at mid-calf through a full day of sitting and walking, without leaving a mark on the leg.

Combed cotton, knitted slowly. Vintage machines run slower than modern ones and give the fabric a denser, softer hand. Combed cotton breathes and does not pill, so the sock looks the same after a season of weekly wear.

One size, on purpose. One size for men (EU 40 to 46) and one for women (EU 36 to 41). The cotton blend has enough stretch to fit comfortably across the range, and it keeps buying simple, for yourself or for someone else.

Frequently asked questions

What colour socks should I wear with business casual?

Start with navy, charcoal grey, black or khaki, matched to the trouser. Once that feels easy, add a quiet stripe or a two-tone block where one colour picks up something you are already wearing. Save bright, full-leg patterns for Fridays or sneaker offices.

Should business casual socks match the shoes or the trousers?

Either works. Matching the trouser gives the most discreet look, because the leg reads as one line when you sit down. Matching the shoe is a little sharper. The thing to avoid is a sock that contrasts with both by accident.

Are crew socks appropriate for the office?

Yes, crew is the right height for the office. It sits mid-calf, so no skin shows when the trouser rides up as you sit. Ankle and no show socks are for summer, sneakers and loafers without socks, not for a desk.

What are the most comfortable socks to wear all day at work?

A crew sock in combed cotton with a hand-linked toe and a ribbed cuff that holds without squeezing. The cotton breathes, the flat toe seam does not rub inside a leather shoe, and the cuff stays put. In winter, a cashmere and merino blend adds warmth without bulk.

Can I wear cashmere socks with leather shoes?

Ours, yes. They are knitted fine, in a crew height with a light rib, so they fit inside a loafer or derby like a cotton sock. Most wool socks are too thick for this, which is the main reason we make ours the way we do.

How should I wash socks I wear to the office every week?

Cotton socks: machine wash at 30°C, inside out, and air dry. Cashmere socks: hand wash or a cool wool cycle, then dry flat. Skipping the tumble dryer is what keeps the colour, the shape and the cuff elastic over a long season.

Escuyer. Considered design, made to last.