This article provides an overview of how many Marriott points are needed to book a free room. Specifically, it states that 30,000 points are needed to book a free room at a Category 1 property, 45,000 points for a Category 2 property, and 60,000 points for a Category 3 property. So, the answer to the question is 30,000, 45,000 and 60,000 Marriott points, respectively, for free rooms at Category 1, 2 and 3 properties. ...