Metallica’s The Black Album had sold 16.4 million copies in the United States by 2016, according to Nielsen SoundScan-era figures.
That total made it the best-selling album in the United States since Nielsen SoundScan tracking began in 1991. The album’s sales were especially notable because it continued moving substantial numbers long after its original release.
The record also became the first album of the SoundScan era to pass 16 million US sales. About 5.8 million of its US copies had been purchased on cassette, illustrating how strongly it connected with listeners during the early 1990s physical-media market.
Later certifications and reporting use different measures, including shipments rather than consumer sales. That distinction explains why figures associated with the album can vary. The 16.4 million figure specifically refers to the cited US sales total through 2016.