Dress codes explained, from white tie to casual

Start with the attire line, usually printed near the bottom of the card or on the event website. Take its words literally: "black tie" is a rule, "black tie optional" an offer to choose, and "black tie preferred" a hint that the hosts would like the dressier choice. When there is no attire line at all, the event itself has to tell you.

Three clues do most of the work. The start time: anything that begins after six in the evening dresses up a level, and black tie by tradition belongs to the evening. The place: a private club, a cathedral or a grand hotel raises the bar, while a park pavilion or a brewery lowers it. The card itself: heavy, engraved or letterpress stock signals a formal event, a digital invite full of emoji does not.

When the clues still disagree, ask the host or someone close to them; it is an ordinary question and nobody minds it. Failing that, aim one level above your best guess. A tie can go into a pocket and a jacket can hang on a chair, but a guest in jeans has no way to add a jacket at the door. Weddings have their own extra hints, covered in what to wear to a wedding.

White tie is the most formal code in Western dress and the rarest. It appears at state banquets in some monarchies, at some charity and opera balls and a handful of traditional galas, always in the evening. If you receive one, expect a strict code with very little room for interpretation.

For men it means a black tailcoat, cut short at the front with two tails at the back and worn open. Under it go a white wing-collar shirt with a stiff front, a white piqué waistcoat that does not show below the coat, and a white piqué bow tie. The black trousers carry two stripes of satin or braid down the outer seam, and the shoes are black patent leather. A tuxedo, however good, belongs to a different code.

For women the rule is a floor-length evening gown. Long gloves reaching above the elbow are the traditional companion, taken off to eat, and this is the one occasion for your most formal jewelry. Cocktail lengths, jumpsuits and separates are not part of white tie.

Black tie is the classic evening formal code, used by most formal weddings, galas and award dinners. Men wear a tuxedo, also called a dinner jacket, in black or midnight navy, with lapels faced in satin or grosgrain, trousers with a single stripe, a white dress shirt with studs or hidden buttons, a black silk bow tie, and a cummerbund or a low-cut waistcoat. Shoes are black patent or highly polished leather. In summer and in warm climates, a white or ivory dinner jacket over black trousers is the traditional variation.

Women wear a floor-length gown, which is always correct. Many black-tie events also accept a very dressy cocktail dress or elegant evening separates in a rich fabric such as satin, velvet or crepe, while a short daytime dress or a work suit falls short. Out of bounds for everyone: a regular business suit, sneakers, and anything you would wear to the office.

"Black tie optional" means the hosts will wear black tie and you may join them or take the step below: a dark suit in charcoal, navy or black with a conservative tie for men; a gown, a dressy cocktail dress or polished separates for women. "Creative black tie" keeps the formality but invites personality, such as a velvet dinner jacket, a patterned bow tie or a dark shirt for men, and a bold color, a dramatic sleeve or statement jewelry for women. For weddings with either line, see the formal wedding guest outfits.

On its own, "formal" usually sits one step below black tie, close to black tie optional. Men wear a dark suit with a white or pale shirt, a silk tie and dark leather dress shoes; a tuxedo is welcome at an evening event but not required. Women have the widest choice here: a long gown, a midi or knee-length dress in silk, satin or crepe, or a tailored evening jumpsuit. Leave out sport coats with odd trousers, open collars and casual sandals.

Formal is also the code where the occasion matters most. A formal daytime event, such as a wedding at noon, allows lighter suits and lighter dress colors; a formal evening calls for dark suits and deeper shades. A funeral is formal in its own way, quiet and modest rather than festive, with its own advice on what to wear to a funeral. The dressiest weddings show the code at its most festive: see what to wear to a formal wedding.

Cocktail attire and semi-formal sit in the middle of the ladder and are often used for the same thing: an evening party, a reception or a holiday event where you dress up without going long. Men wear a suit, usually with a tie at a cocktail party and often without one at a semi-formal event; a well-cut blazer over dress trousers works at the relaxed end. Women wear a dress that ends anywhere from the knee to mid-calf, an evening jumpsuit, or silk separates with trousers or a skirt.

What falls outside: a tuxedo or a floor-length gown overshoots, and jeans, sneakers or a plain T-shirt fall short. Cocktail is the more nocturnal of the two, with shorter hemlines, a bit of shine and bolder color; semi-formal stretches to daytime, where a lighter suit or a printed midi dress is right. The semi-formal outfits cover both ends of it.

The office has its own ladder. Business formal is the top rung, used for board meetings, formal business dinners and award events: a dark suit with a tie, a white or light blue shirt and dark leather shoes for men; a dark skirt suit or pantsuit, or a tailored dress with a jacket, and closed-toe pumps for women.

Business professional is the everyday suit code of law firms, banks and many client-facing roles. Suits are still the norm, but colors and patterns can be lighter: a mid-grey suit, a patterned tie, a colored blouse or a sheath dress with a blazer. If you are not sure which of the two an employer means, the job interview outfits show where a suit is the safe answer.

Business casual drops the suit. Men pair chinos or wool trousers with a pressed shirt, adding a sweater or a blazer as the day needs; women wear tailored trousers or a knee-length skirt with a blouse or a knit, or a simple dress, with loafers, flats or low heels. Jeans, sneakers, T-shirts and gym clothes usually fall outside it. It is also the code most courts ask of their jurors; see what to wear to jury duty.

Smart casual mixes something tailored, a blazer, pressed chinos or a pleated skirt, with something easy, such as dark jeans, a knit or a plain T-shirt, and finishes with clean leather shoes or minimal sneakers. It covers many office Fridays, dinners and gallery openings. What does not belong: athletic wear, worn-out sneakers, ripped denim and slogan T-shirts. The smart casual outfits sit right on its line.

"Dressy casual" turns up on party and graduation invitations and sits just above casual: no blazer needed, but a pressed shirt, chinos or a sundress rather than shorts and flip-flops. The graduation outfits are a good picture of it.

"Casual" is the one code where shorts in summer, everyday sneakers and lighter jeans are fine, but it still asks for clean clothes in good repair that suit the place. Casual for a backyard barbecue and casual for a family photo shoot are not the same, which is why the family picture outfit ideas plan a palette as carefully as a dressier code would.