But an article in The Guardian UK in June 2018 stated that the average earnings of professional authors fall below the minimum wage at around £10,500 (approximately US$13,000). And it's often reported that the average book will sell fewer than 500 copies, which of course, is not enough for a sustainable income. Of course, the top 1% of authors, the ones you know by name, are making more than six figures but most are not earning anywhere near that amount.