Duolingo Offers 40+ Languages. Most of Them Will Waste Your Time.

The app isn't the problem. Your choice of language on it might be.

You open Duolingo, scroll through the language picker, and feel a little thrill. Swahili? Hawaiian? High Valyrian? The catalogue looks like an adventure menu. But here's the thing nobody tells you upfront: picking the wrong language on Duolingo doesn't just slow you down — it can leave you stranded at A1 with no clear path forward, no real-world resources that match your level, and the creeping suspicion that you've been completing lessons rather than learning.

This post is about making that choice well. We'll look at which languages have deep enough courses to actually build a foundation, how far the app realistically takes you on the CEFR scale, and which combinations of language and goal make Duolingo a smart starting point rather than an expensive time sink dressed up as a game.

What CEFR level does Duolingo actually get you to?

Honest answer: roughly A2, with the strongest courses touching the lower edge of B1 — and only if you use the app consistently and supplement it. Duolingo itself has published CEFR alignment data for selected courses (most prominently Spanish and French) suggesting that completing those courses can correlate with B1-level performance on standardised tasks, but the company is careful to note that result depends on engagement depth, not just streaks. For a full breakdown of how the app maps to the CEFR scale, see what CEFR level Duolingo gets you to.

Here's what A2 and low-B1 actually means in practice:

What Duolingo can realistically get you to is a reading and listening foundation — the ability to understand simple, clearly spoken sentences and fill out a basic form. What it cannot do, by design, is get you to hold an unscripted conversation, write formally, or pass a B2 exam. If those are your goals, the app is the runway, not the flight.

• A1: You can introduce yourself and use very familiar phrases. Most thin Duolingo courses stop here in meaningful depth.
• A2: You can handle routine tasks — ordering food, reading signs, simple messages. This is the realistic ceiling for mid-depth courses.
• B1: You can discuss familiar topics with some confidence. Only the deepest Duolingo courses (Spanish, French) have content that can push a motivated learner here.
• B2 and above: Duolingo does not get you here. This requires exam prep, real conversation practice, and structured grammar work.

The single biggest factor: course depth, not your motivation

Duolingo's courses are not equally developed. Spanish has been refined for over a decade, with thousands of sentences, Stories, Podcasts, and grammar tips. Zulu, on the other hand, exists on the platform but has a fraction of the content. Picking a thin course and hoping motivation will compensate is like training for a marathon on a track that's only 200 metres long — you'll run plenty of laps and go nowhere.

Course depth matters because language learning requires massive repetition across varied contexts. A thin course runs out of novel input fast. You hit a wall that feels like your wall, but it's actually the course's wall.

For the current state of Duolingo's catalogue — which courses exist, which have been updated recently, and what features each includes — check Duolingo's own course catalogue directly. Offerings change, and any list a blog posts today can be out of date within months. What we can do here is give you the framework to evaluate any course you find there.

The language table: depth, FSI hours, and realistic Duolingo outcome

The FSI (Foreign Service Institute) hour estimates below are the US government's figures for English speakers reaching professional working proficiency — not fluency from Duolingo. They're useful here because they tell you how hard the language is structurally. A 600-hour language has more forgiving grammar for English speakers; a 2,200-hour language has a writing system and grammar so different that A2 on Duolingo represents a much smaller slice of the total journey.

Course depth ratings (Deep / Mid / Thin) reflect general community consensus and Duolingo's own feature availability as of research time — verify against the current catalogue, since Duolingo updates courses regularly.

Which languages are genuinely worth your time on Duolingo?

Worth it is not just about course depth. It's about the intersection of three things: how deep the course is, how hard the language is for English speakers, and how much real-world material exists at beginner level once you leave the app. Here's the honest breakdown.

Spanish is the clearest yes. The FSI puts it in Category I (the easiest group for English speakers, per the FSI's own published language difficulty rankings), the Duolingo course is the most developed on the platform, and there is an almost unlimited supply of Spanish-language media, podcasts, and conversation partners at every level. If you want a language where Duolingo can genuinely give you a launchpad, this is it. See the best languages to learn in 2027 for how Spanish stacks up across other goals too.

French and Portuguese follow closely. Same FSI category, deep courses, enormous global speaker populations (Ethnologue puts French at roughly 300 million speakers in total and Portuguese at roughly 260 million). Italian is slightly behind — the course is deep, but the ecosystem of beginner content outside the app is smaller.

German is interesting. The course is deep, but the language's grammatical cases mean you'll feel Duolingo's limits faster — the app doesn't drill case endings in a way that sticks. You'll need a grammar-focused supplement from roughly A2 onward.

For Japanese, Korean, and Mandarin: Duolingo is not a waste — it's a genuine first step into the writing system and tones. But you need to go in with clear eyes. The FSI's Category IV designation (2,200+ hours to professional proficiency) means that A1 on Duolingo represents a tiny fraction of the full journey. These languages are worth learning if you have real motivation; they're not worth starting on Duolingo if you're hoping for the same momentum curve as Spanish.

Arabic on Duolingo teaches Modern Standard Arabic, not the spoken dialect of the country you might actually visit or have family ties to. That's a legitimate limitation that most reviews gloss over. Worth knowing before you invest months.

The heritage and minority languages — Irish, Welsh, Hawaiian, Navajo — are a special case. If you have a personal or cultural connection to one of these, Duolingo's course might be the only structured free resource available, which makes it valuable regardless of depth. Just don't expect the same ecosystem of supplementary material.

Is Duolingo enough on its own, or do you need more?

Duolingo is not enough on its own — for any language. This isn't a criticism; it's just what the app is. It's a habit-builder and a vocabulary primer. It is not a full conversation practice tool, a grammar explainer, or an exam prep tool. Treating it as your only resource is like using a highlights reel to learn football. You'll recognise the moves, but you won't be able to play.

The practical answer is to use Duolingo for the first 50–100 hours as a low-friction daily habit, then layer in: a grammar reference (even a free one), listening input at your level (graded readers, podcasts for learners), and speaking practice as early as you can stomach it — even just recording yourself.

If you have a specific goal — passing a DELE, reaching B2 for a job application, communicating with a partner's family — Duolingo should be a small part of a wider plan, not the plan itself. The app's own streak system can create the illusion of progress while you're actually plateauing. Streak days are not CEFR levels.

What the Duolingo Language Report tells us (and what it doesn't)

Duolingo publishes an annual Language Report showing which languages are most studied in each country. It's worth reading — not because it tells you which language to learn, but because it reveals what's driving learner behaviour globally. The report consistently shows Spanish as the most-studied language in the US and many other English-speaking countries, French dominating in parts of Africa and Canada, and Japanese rising sharply among younger learners worldwide.

What the report doesn't tell you is completion rates, actual proficiency outcomes, or how many of those learners are still using the app six months later. Popularity on Duolingo reflects aspiration and cultural interest — both valid reasons to pick a language — but they shouldn't be confused with evidence that the app delivers on those aspirations. Check the latest edition of the Duolingo Language Report yourself for current figures; the landscape shifts year on year.

How to actually choose: a three-question filter

Stop scrolling the picker and answer these three questions first.

One: Do you have a concrete reason to use this language in the next 12 months? Travel, family, work, study? Concrete use cases are the best predictor of long-term motivation — not passion, not the language sounding cool. If you can't name a specific scenario, pick Spanish and revisit later.

Two: Is there a deep Duolingo course for it? Use the table above as a rough guide, then verify on Duolingo's catalogue. If it's thin, you need to know upfront that you'll be supplementing heavily from month two.

Three: What's the FSI category? A Category I language (Spanish, French, Portuguese, Italian, Dutch, Swedish) gives you visible progress fast, which fuels motivation. A Category III or IV language (Japanese, Arabic, Mandarin, Korean) is absolutely worth it if your reason is strong, but you need a longer time horizon and realistic expectations. The FSI's published difficulty rankings for each category are publicly available on the FSI website.

The honest verdict by language type

If you want the fastest visible progress and the deepest course: Spanish or French. Not a controversial pick, but it's the right one for most learners.

If you want a less-common European language with a good course: German, Italian, or Portuguese. All have deep courses and rich supplementary ecosystems.

If you want an East Asian language and you're genuinely committed: Japanese or Korean. The Duolingo courses are decent starting points, but budget for 2,000+ hours to reach real fluency (per the FSI), not 200.

If you want Arabic or Mandarin: start on Duolingo, but pair it with a structured course from week one. The script and tones need more drilling than the app alone provides.

If you want a heritage or minority language: use Duolingo if it's one of your few options, and supplement with community resources wherever you can find them.

Before you start: know your actual starting level

If you already have some knowledge of your target language — school French, childhood Spanish, anything — Duolingo's placement test can place you below where you are, which means you'll spend weeks on content you already know. More importantly, you probably don't know your actual CEFR level, which makes it hard to know when to graduate beyond the app.

If you're working on your English alongside another language, or you want to benchmark where you are before diving into a new one, Nivelo's free 5-minute CEFR test gives you a real level — A1 through C2 — based on the same framework that exams like DELE and Cambridge use. It's worth doing before you commit to a study plan, so you know whether you're building from scratch or levelling up.

The bottom line

Duolingo is a real tool with real limits. The languages worth your time on it are the ones where the course is deep, the language is structurally accessible for English speakers, and you have a genuine reason to use it. That list is shorter than the picker suggests, but it's not short: Spanish, French, Portuguese, German, and Italian all meet the bar.

For everything else, go in with your eyes open. A thin course in a Category IV language isn't a reason not to learn that language — it's a reason to build a smarter plan around it.

For a deeper look at how Duolingo's levels map to real CEFR outcomes, read what CEFR level Duolingo gets you to. For ranking languages by your actual goals — career, travel, culture — see the best languages to learn in 2027. Pick deliberately, measure honestly, and treat the streak as what it is: a warmup timer, not a scoreboard.