Wedding dress codes explained, in plain words

An invitation that says "cocktail attire" is not trying to trick you. It is giving you a level. The trouble is that nobody agrees on the levels, so here they are, from most to least formal.

The codes, ranked

Regional and religious customs change what is appropriate. Modest coverage, colours to avoid and head coverings can all matter.

The 3-2-1 outfit rule

When you stand in front of the wardrobe, decide three things in this order.

1. 3: Time. Before 5 pm leans lighter in colour and fabric. After dark, deeper colours and dressier fabrics.
2. 2: Place. Indoor hall, garden, beach, church or barn. This changes shoes and fabric more than anything else.
3. 1: Code. The word on the invitation sets the length and formality.

If the three disagree, follow the code and adjust the shoes and fabric for the place.

What not to wear

• White, ivory or anything close to the bride's likely colour, unless the invitation says otherwise
• A full black outfit to a daytime ceremony in some cultures, as it can read as mourning. Check with someone who knows the family
• Heels that sink into grass at an outdoor venue
• Anything you cannot sit, dance and hug in

Guests of the couple versus guests of guests

Dress for the invitation, not for your relationship to the couple. Close family may be asked to match a colour scheme, and the couple will tell you. Everyone else should aim to be well dressed and forgettable. The goal is to look good in the photos without being in them for the wrong reason.

When the code is vague

"Dressy casual", "festive", "garden party". Ask the couple or someone close to them what the guests will wear. If you cannot ask, use this decision rule: dress one step above what you would wear to a nice dinner, and bring a layer. You can take off a jacket. You cannot put one on if you left it at home.

Weather and venue

For an outdoor wedding, check the forecast the week before. A shawl, a jacket and shoes that handle grass are not optional extras. For a winter wedding, the weather page on what to wear by temperature covers layers that do not ruin the outfit.

Shoes, bags and the small stuff

Shoes carry the dress code more than people expect. For black tie and formal, closed or dressy shoes in a dark tone. For cocktail, a block heel or a polished flat is fine. For garden or beach venues, a flat or wedge that will not sink. Bring a small bag that holds a phone, a card and lip balm, and nothing else. A big bag at a formal dinner is a chair-back problem for three hours.

Leave at home: a second pair of heels "in case", a large umbrella you will not use if the venue provides cover, and anything that needs ironing on site.

If you are travelling to the wedding

Wear the creasable item on the plane and pack the dress in a garment bag or fold it with tissue paper. Hang it in a steamy bathroom on arrival. For a one-bag trip, the 5-day carry-on list shows how much room one formal outfit takes.