Prince Harry has already made bank from publishing his life story in his memoir "Spare" and could potentially earn millions more in the future, according to a bestselling novelist.

During an episode of his "The Rest Is Entertainment" podcast, "The Thursday Murder Club" author Richard Osman estimated that the Duke of Sussex has already earned around $27 million so far from "Spare" even though only the hardback edition has been released.

"The book that Harry wrote, it's impossible to overestimate how much money that has made," Osman said. "I mean, it's been one of the most successful books. The fastest selling non-fiction book of all time."

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Explaining how he reached this sum, the novelist said it included the reported $20 million advance Prince Harry received for the book and -- based on his publishing industry knowledge -- how much he may have been paid per copy sold.

Osman explained that book authors would only start getting royalties once publishers have earned back the advance they gave.

Based on the sales of "Spare" so far, Osman said he believes Prince Harry has already "earned out an advance of $20 million on the hardback of his first book alone."

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Britain's Prince Harry, Duke of Sussex,
Britain's Prince Harry, Duke of Sussex, speaks during a wheelchair curling demonstration at the "Invictus Games Vancouver Whistler 2025's One Year to Go" winter training camp in Whistler, British Columbia, Canada, February 16, 2024.
(Photo : Don MacKinnon/AFP via Getty Images)

"His book has not come out in paperback yet. So this book is purely hardback. I reckon he's made $26, $27 million," the author said.

Since he's already made back the advance, Prince Harry will simply rake in royalties once "Spare's" paperback edition hits shelves, according to the "Man Who Died Twice" author.

"When the paperback comes out, it's just money rolling into the Sussexes," Osman claimed.

The novelist suggested that a large part of Prince Harry's "huge" earnings from his memoir can be attributed to his strong sales in the U.S., where Osman said the royalties are "absolutely insane."

Penguin Random House has not yet set a release date for the paperback version of "Spare," a spokeswoman for the publisher told the Daily Mail Friday.

In 2021, Prince Harry signed a four-book deal with Penguin Random House reported to be worth up to $40 million.

The Duke of Sussex released the hardcover version of "Spare," the first book within the deal, in January 2023.

"Spare" set a new record for first-day sales after it sold more than 1.43 million copies in the U.S., Canada and the U.K. just 24 hours after hitting shelves, The New York Times reported.

Penguin Random House, the world's largest publisher, said it achieved the biggest first-day sales for any nonfiction book it ever published.

In the first week of its release, the Prince Harry's memoir sold more than 3.2 million copies worldwide across all formats, according to the publisher.

The upcoming paperback version of "Spare" could bump up the net worth of Prince Harry and Meghan Markle, whose combined net worth has grown from an estimated $41 million to $60 million since leaving the royal family in 2020.


Prince Harry and Meghan Markle
Meghan, Duchess of Sussex and Prince Harry, Duke of Sussex arrive at the town hall during the Invictus Games Dusseldorf 2023 - One Year To Go events, on September 06, 2022 in Dusseldorf, Germany.
(Photo : Joshua Sammer/Getty Images for Invictus Games Dusseldorf 2023)

It is unclear what books will be coming out of Prince Harry's deal with Penguin Random House, but he earlier confirmed there won't be a sequel to "Spare," according to Page Six.

Meanwhile, Prince Harry is expected to return to London next month to mark the 10th anniversary of his Invictus Games.

Former royal butler Grant Harrold suggested that the visit could give Prince Harry and his estranged older brother Prince William a chance to "patch things up," with King Charles III possibly playing "peacemaker" for his two sons.

"It is very likely that Harry and William will see each other next month, and anything is possible," Harrold told Sky News Australia.

"Family means everything to the King, like his mother and one of his top priorities will be to ensure that this family rift is healed."