Mr. Fitzwilliam Darcy in Jane Austen's Pride and Prejudice is approximately 28 years old during the events of the novel. Elizabeth Bennet, the female protagonist, is about 20 years old at the beginning of the story, making Mr. Darcy about 8 years older than her. By the end of the novel, Elizabeth turns 21, reducing the age gap to about 7 years. This age difference is inferred from textual clues, such as Darcy mentioning his sister Georgiana's age and other context within the book

. In summary:

• Mr. Darcy's age: ~28 years old
• Elizabeth Bennet's age: ~20 years old at start, 21 by the end
• Age difference: about 7 to 8 years, Darcy being older