The language learning industry sells timelines. "Fluent in 3 months." "Conversational in 30 days." "Master Spanish before your summer holiday." These numbers are not true, and the gap between what is promised and what is realistic is one of the main reasons people give up.
Here is what the research actually says — and what it means in practice for someone learning Polish, Spanish, French, or Korean.
The honest baseline: the US Foreign Service Institute data
The Foreign Service Institute (FSI) trains US diplomats to professional working proficiency in foreign languages. They have been doing this since 1947 and have collected data on how long it takes — for motivated adults, studying full-time with professional instruction.
Their findings, by language group:
Category I (closest to English): approximately 600–750 classroom hours French, Spanish, Italian, Portuguese, Romanian.
Category II (moderate difficulty): approximately 900 classroom hours German, Indonesian, Swahili, and a handful of others.
Category IV (most difficult for English speakers): approximately 2,200 classroom hours Arabic, Chinese, Japanese, Korean.
Polish is not in the FSI data but is generally classified as Category III — approximately 1,100 hours. Linguists who have studied the question place it closer to 1,500 hours for genuine conversational fluency, due to the grammatical complexity.
What this means in practice
2,200 hours is a lot. But it does not mean 2,200 hours of painful study. It means 2,200 hours of meaningful engagement with the language — study, conversation, consumption, practice.
If you study one hour per day, consistently:
- Spanish or French: 2–2.5 years to professional proficiency
- Polish: 3–4 years
- Korean: 5–6 years
Most people do not study one hour per day. They study intermittently — heavily during motivated periods, barely at all during busy ones. This is normal. It stretches the timelines significantly.
A more realistic estimate for motivated but inconsistent learners:
- Spanish or French: 3–5 years to genuine conversational fluency
- Polish: 5–7 years
- Korean: 7–10 years
These numbers are not meant to discourage. They are meant to calibrate. A learner who expects conversational Korean in six months will quit in six months. A learner who expects it in seven years will still be there.
What "fluent" actually means
Part of the problem with timeline discussions is that nobody agrees on what they are measuring.
Tourist survival: enough vocabulary to navigate cafés, transport, and basic shopping. 200–400 words, a handful of set phrases. Achievable in 2–3 months for Spanish and French, 3–6 months for Polish and Korean.
Conversational: can hold a real conversation on familiar topics, understand most of what is said, express yourself without constant pauses. This is what most learners mean when they say "I want to speak X." It takes years, not months.
Fluent: near-native ease and range. Reading literature, understanding rapid speech with unfamiliar accents, navigating any topic. For most adult learners, this takes a decade or more of active use — and many never reach it, nor do they need to.
The FSI figures are for professional working proficiency — closer to conversational than fluent. Even those numbers are large.
Why Polish and Korean are genuinely harder
Spanish and French are close to English in multiple ways: Latin vocabulary base, similar grammatical structures, roughly comparable sentence order. The learning effort is still significant, but you are not starting from scratch in the same way.
Polish and Korean require you to rewire more fundamentally.
Polish has seven grammatical cases — the ending of almost every noun, adjective, and pronoun changes depending on its role in the sentence. This is not just vocabulary; it changes how you have to construct every sentence. Polish pronunciation is also significantly more complex than Spanish, with consonant clusters that require physical practice to produce.
Korean has a grammatical structure that is the reverse of English (subject–object–verb, rather than subject–verb–object), an entirely different writing system, and a complex system of speech levels (formal, informal, honorific) that changes which words you use depending on your relationship to the person you are talking to.
Neither of these things makes the languages impossible. Millions of adults have learned both. But the extra structural distance means extra time — not a little extra, a lot extra.
What actually predicts success
Aptitude matters less than people assume. The research on language learning aptitude suggests that the difference between high-aptitude and low-aptitude learners is roughly a factor of two in speed — not whether they can learn the language, but how quickly.
The things that predict success more reliably:
Starting expectations. Learners who expect a realistic timeline are more likely to still be there when it matters.
Daily contact. Brief daily exposure is worth more than longer sporadic sessions. The spaced repetition effect — where short, frequent exposures consolidate memory better than massed practice — applies to language learning broadly, not just vocabulary.
Willingness to produce before you are ready. Every language learner reaches a point where they know enough to try communicating, but not enough to feel confident doing it. The learners who push through that threshold and start producing — badly, haltingly, embarrassingly — progress faster than the learners who study for one more month before speaking.
Consistency over intensity. A hundred hours spread over a year beats a hundred hours in a single intensive sprint. Memory consolidation requires time. You cannot accelerate it with effort.
The number that actually matters
The timelines above are for professional proficiency. Most learners have a more modest and more achievable goal: being genuinely useful in the language. Navigating real situations without freezing. Having real interactions with real people.
That goal — the one that actually improves travel, opens up relationships, and makes the language feel alive rather than academic — is reachable much faster than the FSI figures suggest. Within the first year, if you focus your practice on production and real scenarios rather than passive study.
The question is not whether you can learn the language. You can. The question is whether you will still be practising in year three. Almost everything else follows from the answer to that.