The record
On 28 June 2021, Duolingo, Inc. filed a Form S-1 registration statement ahead of its initial public offering on the Nasdaq Global Select Market. The filing states that Duolingo had 27.3 million monthly active users in 2019, growing to 36.7 million in 2020 and 39.9 million for the quarter ended 31 March 2021, while paid subscribers grew from 0.9 million in 2019 to 1.6 million in 2020 and 1.8 million by 31 March 2021. The document also states directly that, as of 31 March 2021, approximately 5 percent of monthly active users were paid subscribers to Duolingo Plus, the company's premium ad-free subscription tier.
What the documents establish
The S-1 is Duolingo's own disclosure, and the company states plainly, in the same section defining these metrics, that its monthly and daily active user counts are ‘calculated using internal company data gathered on an analytics platform that we developed and operate’ and ‘have not been validated by an independent third party.’ The filing discloses revenue of 70.8 million dollars in 2019 growing to 161.7 million dollars in 2020, a 129 percent increase, with approximately 73 percent of 2020 revenue coming from Duolingo Plus subscriptions, 17 percent from advertising, and 10 percent from the Duolingo English Test and other sources. Duolingo's SEC EDGAR filing record confirms the S-1 filing date and its subsequent amendment before the offering priced in July 2021.
The operating read
The company's own qualification, that its engagement metrics are unaudited and internally produced, is worth reading before comparing a free-to-paid conversion rate across companies that may define monthly active users differently; this filing's 5 percent figure is issuer-reported, not an independently measured statistic. For an operator running a freemium product, the more durable pattern is the steady climb in paid subscribers as a share of a growing user base, from roughly 3 percent of MAUs in 2019 to 5 percent by early 2021, alongside a revenue mix still concentrated in subscriptions rather than advertising. This is an observation about the shape of the disclosed trend, not a claim that the conversion rate keeps rising, which the filing does not project.
What to check before you decide
A reader comparing engagement or conversion metrics across freemium products should check how each company defines and audits its own numbers before treating them as comparable.
- Does the filing state whether its user metrics are independently validated, or, as here, gathered on an internally built analytics platform without third-party audit?
- Is a conversion percentage computed against monthly active users, daily active users, or another denominator, since the same subscriber count produces different rates depending on which base is used?
- What share of revenue depends on subscription conversion versus advertising or a separate product line, and how might a shift in that mix change the metric's relevance?
Duolingo's own filing states its conversion figure, its revenue mix, and its own caveat that the underlying user counts are unaudited, all in the same document. Reading the caveat alongside the number is the standard the filing itself sets for any comparison drawn from it.
Sources & their limits
These are the existing record’s sources and retrieval dates, preserved from the archive. Source statements, historical events and editorial interpretation are distinct.
- Duolingo, Inc. Form S-1 Registration Statement
States MAU, DAU, and paid-subscriber figures for 2019-2021, the 5% paid-subscriber-to-MAU disclosure, revenue mix, and the company's own caveat that user metrics are unaudited.
- SEC EDGAR Filing History for Duolingo, Inc. (CIK 0001562088)
Confirms the S-1 filing date of 28 June 2021, its accession number, and the S-1/A amendment filed before pricing in July 2021.