How long does Purgatory last?

The Church has not defined whether Purgatory involves duration in the way we experience time on earth. The councils speak of purification and suffering, not of calendars and clocks. Many theologians have speculated about the duration of purgatorial suffering, and the tradition of offering Masses on the third, seventh, and thirtieth day after death (as well as the annual anniversary) reflects the intuition that the process has some temporal character. But the Church warns against applying 'spacio-temporal categories to the dead' (Directory on Popular Piety, §258), and Benedict XVI notes that this 'duration' cannot be calculated in earthly time (Spe Salvi 47). What is certain is that Purgatory is not eternal — every soul in Purgatory will eventually be admitted to the Beatific Vision, and at the latest, Purgatory will end at the General Judgement.