Immanuel Kant books in order
11 books in the catalogue, about 57 hours of reading in all; the shortest takes 1 hour and the longest 14 hours.
11 standalone books in the catalogue.
Standalone books
The Critique of Pure Reason (2 editions) 11.2 h 
The Moral Law 2.6 h 
The Critique of Practical Reason 4.6 h 
The Critique of Judgement 6.2 h 
Perpetual Peace 1.6 h 
Prolegomena to Any Future Metaphysics 4.8 h 
Kant 5.8 h 
Groundwork of the Metaphysic of Morals 2.7 h 
Groundwork of the Metaphysics of Morals 1.4 h 
Grounding for the Metaphysics of Morals ; with, On a Supposed Right to Lie Because of Philanthropic Concerns 1.4 h 
Critique of Pure Reason (The Cambridge Edition of the Works of Immanuel Kant) 14.4 h