Khloe Kardashian has commented slyly about how her youngest sister is now her mother's favourite - after it was revealed Kylie Jenner was on course to become a billionnaire thanks to her hugely successful lip kit company. And now it seems that Kylie's popularity is replicated on Instagram after the social media site revealed each of her posts are worth a cool $1million.

Kendall and Kylie JennerKylie Jenner is the richest of the Kardashian/Jenner clan

A new ranking of the world's top social-media influencers offers some support for how she's accummulated such a massive fortune at such a young age.

The Instagram Rich List, which Instagram-scheduling tool Hopper HQ compiles annually, has Jenner in the number-one spot with an estimated cost per post of $1 million.

The list is based on data gathered through research with influencers, brands, and marketing companies. Jenner's older half-sister Kim Kardashian West is fourth on the list; Hopper HQ estimates her posts are each worth $720,000.

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A few weeks ago, the cover of Forbes featured 20-year-old Kylie, a reality star and founder of the makeup company Kylie Cosmetics, with a cover line proclaiming she is "set to be the youngest-ever self-made billionaire."

Although some people criticised the term "self-made" because of her Kardashian family background, there can be no denying the new mum has done incredibly well.

The youngest daughter of Caitlyn Jenner and Kris Jenner and a star of Keeping Up With the Kardashians, the new mum launched her cosmetics brand two years ago and "has sold more than $630 million worth of makeup since, including an estimated $330 million in 2017," Forbes reports.

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The publication estimates the company is worth nearly $800 million, and Jenner owns 100 percent of it. She's reportedly earned additional millions through her television appearances and by endorsing products including Puma Shows and PacSun clothing, and Forbes estimates she's taken $60 million in after-tax dividends from her company.

In all, that puts her net worth at an estimated $900 million. For that reason, the magazine says that "another year of growth will make her the youngest self-made billionaire ever, male or female, trumping Mark Zuckerberg, who became a billionaire at age 23."