Does Duolingo Work? What the Research Says (2026)

What does Duolingo train, and what does it leave out?

Ratings are our summary of the studies listed further down, checked October 6, 2026.

The pattern is consistent across the research: the more a skill depends on recognizing something, the better Duolingo does with it, and the more a skill depends on producing Spanish on the spot, the less it does.

What does the research say about Duolingo?

Here are the studies most often cited, oldest first, with who ran or paid for each. ACTFL levels are the US proficiency scale; ACTFL's own crosswalk puts Intermediate High reading at about B1 and Novice High speaking at about A1.

Two things stand out. First, the evidence that Duolingo teaches something is solid: every study in the table that tested learners found gains or class-level results, including the independent one. Second, almost all of the large studies come from Duolingo itself. That does not make them wrong, and several were peer reviewed, but it is why the claims you see in Duolingo's marketing ("as effective as classroom learning", "five sections of Duolingo teaches as much as five semesters") deserve a closer look. Those comparisons are about reading and listening. The one large study that tested all four skills found speaking furthest behind.

The independent review by Shortt and colleagues makes a related point from the other side. Of the 35 Duolingo studies published from 2012 to early 2020, most looked at how the app is designed, and few measured what learners could actually do afterwards.

Why does speaking lag behind on Duolingo?

The studies show where the gap is more clearly than why. In the 2024 Duolingo report, Spanish learners who reached the end of the A2 content were rated Intermediate High in reading, Intermediate Mid in listening, Intermediate Low in writing and Novice High in speaking. The authors write that speaking was "approaching Intermediate Low", which is still the weakest of the four.

The learners themselves noticed. In the 2024 Language Learning & Technology study, participants liked the app but pointed to a lack of practical listening, speaking, pronunciation and conversational support. That same study measured some of its biggest gains in speaking and pronunciation, so the app is not doing nothing here. It just starts from zero and gets you to "can say short things", not "can hold a conversation".

Duolingo has tried to close the gap with Video Call, part of its top Max plan, where you talk with the character Lily about anything you like. Duolingo describes it as low pressure on purpose: Lily adjusts to your level, and she does not correct your grammar. That is a fine way to get used to talking, but it means the mistakes you make there are not pointed out.

What does Duolingo do well?

More than its critics usually say. The courses are free, and paying removes ads and adds extras rather than unlocking the course itself. The Spanish course for English speakers is aligned to the CEFR, the A1 to C2 scale schools and exams use, and it runs to the end of B2. Explain My Answer, the feature that tells you why an answer was wrong, used to need the paid Max plan and has been free for everyone since January 2026.

Its biggest strength is the one the studies cannot measure well: it gets people to come back. A course you open every day beats a better course you abandon in week two, and Duolingo is very good at the coming back. If you have a long streak, you already have the habit, and the open question is what to fill those minutes with.

Can you become fluent with Duolingo alone?

Not if fluent means speaking easily with native speakers. The course ends at B2, and the measured outcomes so far show learners understanding far more than they can say. For scale, the US Foreign Service Institute estimates that its full-time students need 30 weeks, or 690 class hours, to reach professional working Spanish, with a teacher and conversation in every lesson. Our guide How long does it take to learn Spanish? breaks those hours down by level and by minutes a day.

So Duolingo can carry you a long way toward understanding Spanish. What it cannot do, by its own data, is replace time spent talking.

Who should add what to Duolingo?

Match the add-on to the gap you feel.

• You can read Spanish but freeze when someone talks to you. Add 10 to 15 minutes of conversation a day. A teacher or a language exchange partner is ideal if you can schedule one. An AI tutor is the easiest daily option. We make Fuego, an AI tutor you talk to by voice or by text: you hold a button and speak, or type, and it keeps the conversation going and corrects you with a short reason. After each conversation the words you struggled with shape your next flashcards. Fuego is a subscription app, and your first conversation with the tutor is free.
• You do not understand real Spanish at real speed. Add podcasts or a series you like, with Spanish subtitles. Course audio is made for learners, and real speech is faster and messier.
• You keep making the same grammar mistake. Use Explain My Answer when it appears, and keep a grammar reference for the two or three topics that keep biting you (for Spanish, usually ser and estar, and the two past tenses).
• You have a trip in three months. Keep the streak, and add a list of common words and phrases for the situations you will meet. Our 1,000 common Spanish words list is free in your browser, sorted into themes, with audio for every word.
• You need a certificate for work or study. Prepare for that exam specifically. Duolingo's course levels are not an official certificate.
• You are not sure where you stand. Take our free Spanish level test, which estimates your CEFR level in about 8 minutes, then decide which gap matters most.

How do you get more out of Duolingo?

Duolingo's own advice and its research point the same way. Its blog says a three-minute lesson keeps a streak alive but longer sessions are what build proficiency, and it asks learners to keep the sound on and not skip the speaking exercises. Its 2024 report adds a detail worth acting on: learners who answered more accurately in their sessions reached higher proficiency, while sheer hours and session counts did not predict a better result.

In practice that means three habits. Do at least one full session a day on top of the streak-saver. Say every speaking exercise out loud, even on a bus, quietly. And when lessons feel too easy, move forward instead of farming review lessons for points. Then, once a week, test yourself outside the app: try to describe your day in Spanish for two minutes without stopping. In the research so far, that is the skill that lags furthest behind.

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