I’m often asked how many hours it takes to learn a foreign language, how many hours the asker should plan to spend on learning language X, (more rarely) how many hours it took me to learn a language. Here’s an attempt at an answer.
It is a difficult question because there are so many variables. You can get a first idea at Wikibooks:Language Learning Difficulty for English Speakers, because the language you’re learning (and the language(s) you speak already) are the most important factors. If you’re Chinese and trying to learn Dutch, you may need more than 2000 hours, while as a native English speaker you only need around 600 – and if you’re a native German speaker with some knowledge of English, you may be able to make do with 300 even!
So that table is not the end-all of estimates; it also depends on which languages you have learned already and if you have any experience at all in learning languages. The first foreign language is always the hardest, which is why Benny Lewis (author of “Fluent in 3 Months”) and I recommend spending at least 2 weeks learning Esperanto (which is completely regular and easy) in order to wrap your head around a lot of features that would be much harder to figure out when learning a less regular language.
Apart from your language knowledge and experience, the next biggest factor is the level you’re trying to reach. The numbers on the site I gave are all going for the lower end of professional working capacity. If you have a less lofty goal, you may be able to reach it faster, especially if you optimize for what you want to achieve. As you can read in this blog article I wrote for Benny’s site, I have been able to understand a Japanese TV series after 30 days, test at A2 level in Finnish after 30 days, give a public speech in Indonesian after 6 weeks, and so on. It’s all a matter of optimization for your goal. Few people really want to be an expert at every aspect of a language, at least not urgently. They urgently need one skill, but they develop all skills at once because that’s what textbooks and classes generally do. It slows them down a lot though. When I needed to urgently get comfortable reading Spanish in order to quote Spanish linguistics journals for my thesis, I reached that level in a few dozen hours of study rather than the 575+ that the FSI cites – but I don’t have professional working capacity in Spanish, I just learned enough for my purposes. It’s another example of the optimization I’ll do, accepting lopsided language knowledge in exchange for achieving surprising feats very quickly. Unfortunately, you don’t really get an idea of how to optimize your path until you’re already an experienced language learner. Here a coach may be helpful.
Note also that intensity is an issue. The FSI assumes that you will study very intensively, as their students do, at least 4 hours a day. However, the average adult language learner only studies two hours a week or so. At that speed, you will forget much more and waste time having to review it, so you will inevitably need longer than their estimates. The more intensively you study, the less total time you’ll need. I recommend intensive study especially at the beginning, to quickly leave the textbook stage behind and reach a level where “study” becomes self-motivating and fun, for example because you’re watching movies or reading interesting articles in your target language.
And that’s the real key: motivation. The more weeks and months you spend on a language, the more motivation you need in order not to quit. The vast majority of language learners quit before they reach their goal. So ensure that either a) the language is easy enough to pick up quickly or b) you’re studying very intensively or c) you have enough motivation to sustain you for the really long run.