From Twentieth Century Fox Home Entertainment:

Twentieth Century Fox Home Entertainment sold 1.5 million Blu-ray units of James Cameron's Avatar on Earth Day, the film's first day of home video release. The 1.5 million units is a new record, topping The Dark Knight's 600,000 Blu-ray units sold its first day in 2008.

The studio expects to sell well over 4 million combined Blu-ray and DVD units of the movie.

Retailers sold out of 60% of their Blu-ray inventory, while they moved out about 50% of their Avatar DVDs.