John Mayer blew 25% of his net worth on expensive watches

It's a good thing John Mayer is wealthy, because he has a very expensive watch habit.

Within Hollywood, the seven-time Grammy winner isn't recognized for only his music, but also for his status as a watch aficionado and collector, otherwise known as a horologist — an obsession explored on an upcoming episode of CNBC's "The Filthy Rich Guide."

John Mayer
Scott Dudelson | Contributor | Getty Images
John Mayer

In Mayer's impressive collection, a single watch can cost hundreds of thousands of dollars. He has one Patek Philippe timepiece that goes for $300,000.

John Mayer's collection includes this Patek Philippe 5970G said to cost $300,000.
Hodinkee | Filthy Rich Guide
John Mayer's collection includes this Patek Philippe 5970G said to cost $300,000.

Though Mayer won't disclose exact numbers, he told The New York Times in 2015 that his collection is valued "in the tens of millions."

"The Filthy Rich Guide" estimates Mayer's net worth to be around $40 million, which makes his watch collection worth at least 25 percent of his wealth. Not exactly a diverse portfolio.

But according to Mayer, the hobby is about more than being able to throw down cash in exchange for fancy timepieces. It's a commitment to learning and understanding the tiniest details and nuances of design.

"I spend probably as much time thinking about or diving into watches as I do anything else," the singer says.

He better always be on time.

Watch CNBC's "The Filthy Rich Guide," Wednesday, May 24th at 10PM/ET.

Don't miss: Billionaire problems: 3 ridiculous situations only the super rich could get themselves into