FSI does say 600 hours for Spanish. It does not mean what you think

Most numbers in this field cannot be sourced. This one can: the Foreign Service Institute publishes how many class hours its students need per language, and Spanish is about 600.

It is the best-attested figure available, it is the foundation of every estimate on this site, and it is quoted wrongly almost everywhere — usually in the direction that makes learning look easier.

Four things the number assumes

1. Class hours, not total time.

600 is instruction. FSI students also do homework, and the usual framing of their programme is around five hours of class a day plus preparation. Somebody counting all study time would report a substantially larger number for the same outcome.

So "600 hours to Spanish" and "600 hours of Duolingo" are not comparable quantities even before the method question.

2. Full-time small-group instruction with qualified teachers.

This is the method our model calls intensive-class and treats as the 1.0× baseline — the fastest realistic option short of living in the country. Every other way of studying costs more:

Quoting 600 at someone studying from an app has changed the method silently.

3. It reaches professional working proficiency, not conversation.

The endpoint is ILR Speaking-3 / Reading-3: arguing a point in your professional field, reading a newspaper unaided. On the CEFR scale we take that as C1, which is a choice with no official basis and the conservative one.

If what you want is B1 — hold a conversation, handle a trip — you need about half of it. Quoting the full figure at someone who wants conversational Spanish overstates their project by a factor of two, and quoting it as "conversational" understates the achievement by the same factor.

4. It is an average over selected, motivated adults.

FSI students are screened, paid to be there, and studying full time under professional instruction. They are not a random sample of anybody, and 600 is a mean over classes with variation around it.

Same caveat as the 10,000-hour rule, which came apart for exactly this reason: an average across a group, quoted as a threshold for an individual.

What the number is genuinely good for

Ratios. This is where FSI data earns its place, and the ratios are far more robust than the absolute figures.

Spanish is 600 hours; Mandarin is 2,200. Whatever assumptions you disagree with about class hours or endpoints, they apply to both — so Mandarin costs roughly 3.7 times what Spanish costs, for you, whoever you are and however you study.

That ratio is the most useful thing in this entire dataset, and it does not depend on any of the four assumptions above. It is why the difficulty table is worth reading even if you think every absolute number on it is wrong.

Using it honestly

• Adjust for your target level. B1 is roughly half of C1, not a rounding difference.
• Adjust for your method. This is the biggest correction and the one most often skipped.
• Treat it as a planning average, not a promise.
• Trust the ratios more than the absolutes.

The calculator applies all of these and shows each adjustment separately, and the methodology says which factors are published figures and which are our estimates. Only the baseline is published.