Slack Technologies is expected to be valued by investors at $16bn to $17bn when it lists its shares publicly next week, according to people familiar with the matter.

That valuation is roughly based on the workplace chat and collaboration software company's projected revenue and current growth rate, said the people, who asked not to be identified discussing private talks.

The expected value is up from the $7.1bn in its last private funding round in August. It's similar to the company's share sales on the private market, where in April investors were snapping up stock at prices that would give the company a valuation of about $16bn.

A spokesperson for Slack declined to comment.

Slack is planning to have its shares start trading June 20 on the New York Stock Exchange under the ticker WORK.

Investors' valuation expectations are based on some back-of-the-envelope math: Slack said on Monday that it expects at least $590m in revenue in its 2020 fiscal year, which ends January. That's a growth rate of as much as 50% compared with the previous year.

Slack files for direct listing on NYSE to sidestep typical IPO

That suggests the company could bring in almost $900m in fiscal year 2021, and investors are looking to value the company at roughly 20 times that projected revenue, the people said.

That's even as the annual revenue growth rate has slowed from 110% and 82% in the 2018 and 2019 fiscal years, respectively, according to a regulatory filing.

Slack said in its filings with the US Securities and Exchange Commission that it can't guarantee that its plans to increase revenue and cut operating losses will ever allow it to become profitable.

Slack is also rolling out partnerships with other software companies. Dropbox, the document-management software developer that went public last year, announced on Tuesday that it had integrated Slack into its workplace product.

Unlike a surge of tech companies that have gone public this year in traditional initial public offerings, Slack is going public through an unusual direct listing. The company won't issue new shares to raise funds for itself. Rather, its investors will be allowed to begin selling existing shares immediately.

New technology stock offerings have been on the upswing this year. On Tuesday, CrowdStrike raised $612m in one of the largest cybersecurity company IPOs ever.

Goldman Sachs Group, Morgan Stanley and Allen & Co are advising Slack on the listing. Bloomberg Beta, the venture capital arm of Bloomberg LP, is an investor in Slack.