Although it has certainly evolved (some might say mutated) over the years, men's formal dress code still maintains clear standards. Once you understand the nature of the invitation, you will be able to put together an outfit that suits the event.
The Basic Formal Dress Code
If the invitation says "black tie optional," it means "formal." Formal dress will vary by time of day, but it will always conform to a certain style. A traditional daytime formal look, also called morning dress, demands a black or gray tailcoat or walking coat with trousers that either match exactly or feature pinstripes. This look, still seen for weddings and formal diplomatic receptions, especially in Europe, also includes a double-breasted vest, long tie, gloves, a boutonniere, tall hat and smart cufflinks.
Evening formal still means the basic tuxedo, but any dark suit can work. Traditionally, the suit is accompanied by a white shirt, dark tie, dark socks and shoes. This can vary depending upon the event. Many men prefer a tie with a bright color or pattern, worn with a matching handkerchief. Not only is a suit and long tie often more flattering than a tuxedo, especially if that tux is not tailored to fit exactly, but it can be more comfortable and allow a man to express more of his individuality. However, it is important that the tie be of exceptional quality. Only a silk tie, preferably tied with a classic knot, is acceptable when choosing this look for a formal evening occasion.
Variations in the Formal Dress Code
In the modern era, when black tie events such as the Oscars allow for even casual dress, what is formal is not always strictly defined or adhered to. A man might wear semi-formal or cocktail attire, for example, and not feel out of place, whereas in the 1940s, he might not have been allowed into the function.
Formal wear for an outdoor summer wedding these days might mean a good linen or silk suit. However, these must be worn with a tie. Formal wear simply does not allow for even the most expensive T-shirt or open collar dress shirt.
For an evening event, the standard formal dress code is still a dark suit, although again, if you are going to be outdoors in summer, you can feel free to add some variations, depending on the nature of the event. That is, you should still wear a suit and tie and dressy shoes, but you can wear a light dress shirt in a contrasting color and a patterned silk tie.
Other ways to play with your look include having fun with accessories. Instead of plain cufflinks, opt for something vintage or artistic. An outdoor summer event might allow for a trendy belt, rather than something classic, so long as it doesn't clash with your attire. Swap a dress hat for a straw boater or Panama for a 1920s look.
Assess the Event
If you are going to bend the formal dress code, you need to know the nature of the event and the people hosting. If the occasion is of an artistic nature, then you can feel very comfortable going wild, so long as you still look respectable. A very traditional wedding or reception, however, will demand that you adhere to stricter standards. And anything official means you have to dress the part faultlessly. If you're not sure if your suit will fit the bill, you can go to a high-end menswear shop and ask advice - the salespeople will be happy to help you. With a good, well-fitting suit and shirt, matching tie and dress shoes, you can feel confident of looking appropriate.