Six grand tournaments are held each year, alternating between Tokyo, Osaka, Nagoya and Fukuoka. Because each one has its own published sale date, the common advice to book a fixed number of weeks ahead is simply wrong for some tournaments and wastefully early for others.
In the schedule published at the time of checking, the distance between the advance-sale date and the first day ranged from under a month to close to two months depending on the tournament. That is why this page sends you to the official table rather than storing a formula.



