The dress codes, from most to least formal
White tie
The rarest and most formal. Women: full-length ball gowns, long gloves optional. Men: black tailcoat, white bow tie, white waistcoat. If you see this code, it is a grand evening affair — dress accordingly.
Black tie
Women: floor-length gowns or dressy cocktail dresses. Men: tuxedo with bow tie. The classic evening-wedding code.
Black tie optional / Formal
Women: long dresses or elevated cocktail dresses. Men: tuxedo preferred, dark suit acceptable. When in doubt at this level, lean formal.
Cocktail
Women: knee-to-midi cocktail dresses or dressy separates. Men: suit and tie. The default for most evening weddings.
Semi-formal / Dressy casual
Women: sundresses, midi skirts, polished separates. Men: blazer or sport coat with trousers; tie optional. The most flexible code — neat and celebratory beats trendy.
Casual
Women: summer dresses, nice separates. Men: chinos and a collared shirt. Still a wedding: skip shorts, tank tops, and flip-flops.
Beach / Destination formal
Lightweight, wind-friendly fabrics; sandals over heels; linen suits without ties. Formality comes from polish, not weight.
The unwritten rules behind the codes
Dress codes describe a range, and guests are expected to land inside it — not at its edges. A cocktail dress code tolerates both a simple sheath and a beaded midi, but not a ballgown and not jeans. Time of day matters too: the same "semi-formal" reads dressier at 7 p.m. than at 2 p.m. And cultural or religious venues may add requirements — covered shoulders, head coverings — that outrank the printed code, so check the venue as well as the invitation.