Tell them what to wear,
and nobody has to ask.

Every guest asks the question. Most of them do not ask you. They ask the friend who is also invited, or the group chat, and the answer that comes back is a guess. A dress code is that answer given once, by the only people who actually know.

It carries more than clothing. Black tie also tells a guest that dinner will be sat down, that there will be speeches, and that the evening is long. Garden party tells them the ground is soft and there will be standing. Guests read those signals even when they could not name them, which is why two words at the foot of an invitation do more work than a paragraph about the schedule.

Leaving it blank does not relax anybody. With nothing written, guests default to the venue, and a venue is easy to misread: a converted barn photographs rustic and turns out to be black tie, a town hall photographs formal and turns out to be lunch in a garden. Somebody arrives overdressed and spends the day apologising for it.

Here is what each level asks of a guest who owns one good suit or one good dress, which is most guests. White tie is genuinely rare: tailcoats, long gloves, and a hire shop for nearly everyone. Black tie means a dinner jacket and a bow tie, and a long dress or a formal short one. It is the level an ordinary dark suit does not quite cover, and hiring for the evening is completely normal.

Black tie optional is the useful compromise and the most misread phrase on the list. It means the hosts and the wedding party will be in black tie, you are welcome to be, and a dark suit with a tie is complete and correct. Write it when you want the photographs to look a certain way without asking eighty people to spend money.

Formal, or lounge suit, means an ordinary suit: day wear, not evening wear. The phrase confuses people outside the countries that use it, so if your guest list crosses borders, add three words of description rather than trusting the label. Cocktail sits just below, and it is a step down from black tie rather than a step up from smart casual, which is the mistake most guests make. Smart casual is the vaguest of the lot: the safest reading is what you would wear to a good restaurant, and no trainers unless you say so.

Garden party or summer attire is about fabric and footwear more than formality: lighter colours, something with sleeves for later, and shoes that survive grass. A theme, whether twenties, black and white or a single colour, is a request for effort, so it needs an example and a way out in the same breath. Twenties, as much or as little as you like gets a room that looks the part without anyone dreading the month before.

The first is the floor. Grass, gravel and cobbles decide what your guests can put on their feet before formality gets a say, and a stiletto on a lawn is a ruined afternoon. If any part of the day stands outside, whether that is the ceremony, the drinks or the photographs, write it next to the code. Formal, and the ceremony is on grass is more useful to half your list than the word formal on its own.

The second is the weather and the length of the day. A wedding runs from an afternoon ceremony to a late night, and the temperature at the end is not the temperature at the start. Outdoor drinks in spring need a jacket nobody packed. In real heat the code bends whether you like it or not, so bend it yourself and say so; guests follow the hosts and are grateful for the permission.

The third is the ceremony itself. In some places a religious ceremony comes with expectations of its own, such as covered shoulders and knees or a covered head, and those belong to the building rather than to you. Write them that way. The church asks that shoulders are covered during the ceremony lands very differently from guests must cover their shoulders, and it also tells guests they can take the wrap off afterwards, which is the part they wanted to know.

Short works. The shortest version is the level and a full stop: Black tie. Cocktail attire. Lounge suit. If the level does the work, leave it alone, because guests who need more will go looking for more.

One step up, add the reason or the constraint, because a reason makes people cooperate. Black tie, and it is a long dinner. Formal, and the ceremony is on grass, so flat or block heels. A step further, write a friendly sentence in your own voice: wear something you feel good in, most people will be in suits and dresses, and the ground is soft, so plan your shoes. All three are correct. The only wrong version is the one that sounds like a rule book.

Two things to avoid. No dress code reads as a trap, because guests assume there is one and that you are being polite about it; if you genuinely do not mind, say what you will be wearing and let them calibrate. And do not stack prohibitions, because a list of four things not to wear makes guests more anxious rather than less, and produces exactly the messages the line was meant to prevent. The wedding invitation wording guide sets out the rest of the invitation in order, and the dress code is the last line, under the reply line.

An invitation has room for two words. The questions behind them have paragraphs, and they arrive in the fortnight before the day: is the grass wet, is there anywhere to leave a coat, is the after-party the same clothes, what does cocktail actually mean. Split the job. The invitation carries the level, and the guest page carries everything the level implies.

That page is where guests already look for the schedule, the directions and the hotel suggestions, so the dress code belongs with them rather than in a message nobody kept. A short note, a sentence of description and a line about shoes answer most of it, and a questions section takes the rest, so the same answer reaches everyone instead of one person at a time. There is a longer piece on what belongs on a wedding guest information page and what does not.

The vocabulary is the other reason to write more than the label. These terms travel badly between languages: several have no exact equivalent, and the nearest word often sits a level above or below the one you meant. Guests read the page in their own language, so give the translation a plain sentence to work with rather than two words.

Children first, because a parent reading black tie will either buy a small waistcoat or spend a week worrying about it. Say it in the same line: black tie for the adults, comfortable for the children. That sentence quietly answers whether children are invited at all, which is the other thing that parent wanted to know.

Older relatives are often the best dressed people in the room and the most likely to ask. Someone in the outfit she has worn to every family wedding for thirty years is correctly dressed at any level, and it is worth telling her so. There is also always a guest coming straight from work or off a train. Give them the answer before they have to ask for it: if you are coming from work you are fine as you are, or there is a room at the venue if you want to change.

Guests who travel have a third problem, which is that the code has to fit in a suitcase and a hired dinner jacket does not cross a border easily. If a real part of your list is flying in, either choose a level they can pack or decide early enough that they can plan around it. Anything that asks guests to buy or hire is a cost you are placing on them, worth naming while you are still choosing.

In some places guests avoid white without being asked. In others the convention does not exist, or white means something quite different. Your guest list may hold both kinds of guest and neither is being rude. So if it matters to you, ask once, warmly, with the reason attached. We would love to be the only ones in white that day does the job. Guests must not wear white does the job too, and costs you something.

The same is true of every other request. No black reads as reasonable to some guests and superstitious to others. A colour palette for the photographs is a real ask, and people will do it if you tell them why and give them a range rather than a single shade. One request lands. Three requests make an invitation read like terms and conditions, and a guest who feels tested asks more questions, not fewer.

Whatever you ask, ask it in the same place as the code rather than in a separate message a fortnight later. A request that arrives on its own reads as a complaint about something somebody has already done.

Codes change more often than anyone expects. The ceremony moves indoors, the date shifts into a colder month, the plan gets simpler and black tie stops making sense. This is the moment printed stationery becomes expensive: a card inside an envelope cannot be corrected, and the only fix is a second message that some guests read and some do not, which leaves two versions of the truth in circulation.

A link does not have that problem. The invitation is a live page, so the line is changed once and every guest who opens it sees the new version, including the ones who opened it a month ago. That is worth doing even when you have sent a message as well, because the message gets scrolled past and the page gets checked the night before.

Two practical notes. Change it three weeks out if you can, because that is when people start buying and booking hire. And if it is later than that, soften rather than raise: dropping from black tie to a lounge suit costs your guests nothing, while raising the level late costs all of them at once. If the day is split into parts your guests reply to separately, such as the ceremony, the dinner and the after-party, say where the clothes change between them, and put it beside the timings in the order of the day.