Nielsen SoundScan reported that Metallica's self-titled album sold 598,000 copies in its first US week.
The figure belongs to the album's initial 1991 release and helped explain why it debuted at number one on the Billboard 200. SoundScan tracking used retail purchase data, providing a more systematic way to measure sales than older reporting methods.
The first-week total was only the beginning of the album's commercial story. Metallica continued selling for decades, eventually becoming the best-selling album in the United States of the Nielsen SoundScan era and passing 20 million US copies shipped by 2025 according to its certification history.
First-week sales are distinct from lifetime sales and from worldwide totals. They measure the album's opening seven-day performance in the United States, not every copy sold over its entire history.