Heavyweight finance publication Forbes has been forced to explain why it chose Kylie Jenner as cover girl for its new America’s Women Billionaires issue.

No sooner had makeup mogul Jenner, 20, hit newsstands in a serious designer business suit than Forbes faced a backlash.

The magazine estimated Jenner’s net worth to be around $US900 million, making her the 27th richest self-made woman in the US.

Three years after she launched Kylie Cosmetics, Jenner’s net worth now easily eclipses that of anyone else in her family, including her sister Kim Kardashian West.

She’s also about to take down Facebook’s Mark Zuckerberg – who was 23 – as the “youngest self-made billionaire ever”, Forbes reported.

“I couldn’t have dreamt this up,” the mogul, who isn’t old enough to drink alcohol in the US, said on Instagram about making the list.

The problem? The definition of “self-made’, a description of Jenner that had dictionary.com leading a Twitter stampede to throw shade.

Self-made means having succeeded in life unaided.

Used in a sentence: Forbes says that Kylie Jenner is a self-made woman. https://t.co/sr8Ncd7s5A https://t.co/ehEL7Cf6KV

— Dictionary.com (@Dictionarycom) July 11, 2018

“Calling Kylie Jenner self-made without acknowledging anywhere the incredible head start she had is what allows people to turn around and look at poor people and ask them why they haven’t become billionaires yet,” one user, Lola Adewuya, wrote on Twitter.

“Her story is not inspiring or motivating for anyone.”

Another Twitter user responded: “Does that say self made? On what planet is Kylie Jenner self made?”

Forbes fought its corner.

“We consider any person who built her own fortune, and didn’t inherit the money, to be self-made,” it said of its methodology and calculations.

“So top executives at tech firms who are compensated for helping significantly grow companies make the ranks but not second-generation women running family businesses.”

By that definition, Jenner fits the bill, despite her ritzy back story.

The daughter of Hollywood’s most famous ‘momager’ Kris Jenner and Olympic gold medallist Caitlyn Jenner, Kylie literally grew up on the reality TV show Keeping up with the Kardashians.

She turned her “lifelong” obsession with makeup into an empire almost by default after watching sister Kendall launch an international modelling career.

“I struggled for a minute with finding something to do on my own,” she told Forbes.

Jenner put up a reported $US250,000 of money earned from modelling jobs to produce her initial product, the $US29 Kylie Lip Kit.

“I was like ‘OK, if this doesn’t work out you’re gonna have, like, a lot of Lip Kits in your garage,'” she said in a June video for Vogue.

The 15,000-strong first run of products sold out in seconds.

“Like, I just remember me and all my glam people, my friends, we were like screaming,” said Jenner, who has added other lines including eye shadow and concealer.

“I was like, ‘This is like gonna be something, like, I can actually do, yeah’.”

In its cover story, Forbes estimated Kylie Cosmetics has made $US630 million since its 2015 launch, and conservatively valued the company at nearly $US800 million.

Jenner is the face and sole owner. She credited her 110 million Instagram and 25.6 million Facebook followers with her success: “I have such easy access to my fans and my customers.”

She’s earned millions from TV shows and Puma endorsements, and Forbes added another $US60 million in “estimated after-tax dividends she’s taken from her company”.

The end result? “She’s conservatively worth $US900 million, which along with her age makes her the youngest person on the fourth annual ranking of America’s Richest Self-Made Women,” the story said.

Despite its runaway success, Kylie Cosmetics employs only seven full-time and five part-time staff. Production and sales are outsourced.

Kris Jenner takes a reported 10 per cent fee for handling her youngest daughter’s finances and PR.

Jenner told Forbes she wants to run Kylie Cosmetics “forever” and has a succession plan involving Stormi, her five-month-old daughter with rapper Travis Scott.

“Maybe one day [I’ll] pass this on to Stormi, if she’s into it.”

Despite being relegated in the family wealth stakes, Jenner’s sisters and mother celebrated their little “boss” on social media.

“I am so proud of you and everything you have accomplished,” her mother, Kris Jenner, wrote on Instagram.

“You work so tirelessly on your business, and with so much passion and precision.

“As a mother, it brings me immense joy to watch you continue to make your Kylie Cosmetics dreams a reality.”

“Billion dollar baby!!!!!” Kardashian West tweeted.