Amazon.com's book sales grew 46% to $3bn (£2.33bn) in the first half of 2017, while e-book sales increased 6% to $750m, making the book sector a "stable contributor" to the company's overall success, according to e-commerce company One Click Retail.
One Click Retail uses a combination of website indexing, machine learning and proprietary software to estimate weekly online sales figures for Amazon. Its research determined that Amazon.com netted $136bn (£105.8bn) worth of sales across all categories in 2016. Of this total, it estimated that Amazon's print book sales amounted to $4.7bn and e-book sales were $1.4bn in 2016.
In the first half of 2017, One Click Retail estimated that print book sales grew by 46% to $3bn (£2.33bn) compared to the same period in 2016 ($2bn). The children’s books category was the highlight of the first halves of 2016 and 2017 alike, with a 45% year-on-year growth up from $320m (£249m) to $460m (£357m) in 2017, due to the success of J K Rowling's Harry Potter and the Cursed Child (Little, Brown).
The next top performing print book category on Amazon.com was religion and spirituality, which saw a 55% year-on-year growth rate from $200m (£155m) sales in the first half of 2016 to $315m (£245m) in 2017.
Harry Potter and the Cursed Child was the retailer's bestselling title of 2016, according to One Click Retail, while the Harry Potter complete paperback book set came in second place. StrengthsFinder by Tom Ruth was third and fourth was Hamilton: The Revolution by Lin-Manuel Miranda and Jeremy McCarter. Rounding out the top five was The Whole 30: The 30-Day Guide to Total Health and Food Freedom by Dallas Hartwig and Melissa Hartwig.
Sales of e-books meanwhile experienced a 6% year-on-year increase from $710m (£552m) in the first half of 2016 to $750m (£583m) in the same period in 2017. Top selling e-books in order were Hillbilly Elegy: A Memoir of a Family and Culture in Crisis by J. D. Vance, Camino Island by John Grisham, A Man Called Ove by Fredrik Backman, A Gentleman in Moscow by Amor Towles, and James Patterson’s The Black Book.
In the UK, Amazon's print book sales for the first half of 2017 grossed £360m, according to One Click Retail. The top three Amazon print book sellers in the UK - Mary Berry Everyday (BBC Books), Tom Kerridge’s Dopamine Diet (Bloomsbury), Lean in 15: The Shift Plan by Joe Wicks (Bluebird) - show non-fiction lifestyle titles are popular. This is in keeping with Amazon Summer Trends report which revealed the 10 bestselling print titles for the first six months of 2017 were dominated by non-fiction titles.
Meanwhile, e-books grossed £100m in the UK for the first half of 2017 with bestsellers Night School by Lee Child (Bantam), Apple Tree Yard by Louise Doughty (Faber), The Girl on the Train by Paula Hawkins (Doubleday), Lion: A Long Way Home by Saroo Brierley (Penguin) and The Gift by Louise Jensen (Bookouture). According to One Click Retail, crime, thrillers and mystery is the most popular category for e-books.