How many copies of Metallica's self-titled 1991 album were sold worldwide on physical media?

Metallica's self-titled 1991 album sold 31 million copies worldwide on physical media.

That figure helps explain why the record is regarded as one of the most commercially successful albums in heavy-metal history. Its sales were spread across formats including compact discs, cassettes, and vinyl, with the album continuing to sell long after its initial release.

In the United States, the album became especially significant during the Nielsen SoundScan era. It passed 16 million US copies by 2016 and was later certified 2× Diamond by the Recording Industry Association of America for shipping 20 million units in the country.

The worldwide physical-media figure should not be confused with a single country's certification or with streaming totals. The album also accumulated more than 30 million copies in broader worldwide estimates, while the specific physical-media figure reported for the release is 31 million. Its enduring sales helped make it the band's best-selling album.