What is my Sun sign?
The Sun spends about a month in each sign, so the date is usually enough. Born within a day of a boundary? This works it out from the real position rather than a table of dates, which is where the year matters.
Calculez pour placer le signe : suivent une carte du ciel et une courte lecture.
Why a date is usually enough
The Sun covers about one degree a day, so it holds a sign for roughly a month. Almost everybody can read their Sun sign off the date alone. The exception is a birthday within a day or so of a sign change: the boundary falls at a different hour each year, which is why a table of dates gets those people wrong and a real ephemeris does not. A birth time adds the house — which part of life the Sun's business shows up in — and nothing else.