Start with the time of day. Events in the morning and early afternoon rarely require evening attire, and more often call for business or cocktail looks. Ceremonies that start in the evening, especially in a hotel or an elegant venue, raise expectations. It is not a rigid rule, but it works surprisingly often. If the invitation says “dinner” and the start is at 19:00, then a shirt and blazer are the minimum safe level.
The second signal is the venue. A restaurant with white tablecloths, a ballroom, a philharmonic hall, a gala at a conference centre, all suggest a higher level of formality. Outdoors, a garden, a relaxed corporate event often allows smart casual. But note: outdoors does not mean sloppy. Outdoors, fabric and comfort matter, for example lighter wool, cotton, or linen in a blazer, not a resignation from elegance.
The third thing is the role you play. A guest dresses differently than a best man, differently than someone who will speak on stage or host a meeting. If you are meant to be the “face” of the event, it is better to raise formality by half a step. It is a simple trick that saves you when the dress code is vague. Then even if others are more relaxed, you still look appropriate because your role justifies it.
If you still do not know what the author means, ask, but do it with class. Instead of writing “what should I wear?”, ask: “Should I wear a suit, or will a blazer and tailored trousers be enough?”. The question is specific, and at the same time shows you understand levels of formality. In 90% of cases you will get a clear answer, and the stress disappears.
Finally, a small “reality test”: if the invitation includes a request for a shared colour palette (for example navy and white) or information about photography, it is a sign the organiser cares about cohesion. Then it is better to stick with the classics. And classics are often the simplest route: a well-cut blazer, tailored trousers, a shirt, and polished accessories.