How long does it take everyone to complete a language?
It took me 3 months to complete the Duolingo course of French. I had never learned French before. English helped a lot (my native language is Russian, so English and French have much in common for me). Of course, mastering all the Duolingo levels is not equal to mastering the language, but it's a good start :)
I agree it is different for everyone. It took me about 25 days to complete spanish. It was relatively easy for me because I already knew Portuguese. I am a big fan of Duolingo. I am going to try and complete french next and then German. And hopefully Mandarin (please Duolingo!!)
This is a different answer for everyone depending on what languages you already know, time you put in, how hard is the target language and so forth, from my own experience, I was a native in spanish, I was able to carry small conversations in less than a year and from there I picked up the language mostly by immersion. English is easier compared to spanish, the path I follow to learn a new language is alphabet, pronunciation, grammar rules, vocabulary, read and write basic sentences, listen to audio, watch movies, then I start talking to native speakers once I feel comfortable talking even thou I know mistakes are bound to happen. Always keep a dictionary by you as well.
There are different definitions of finishing. Finishing all the skills units... That plus turning the whole tree golden, or hitting the highest level, level 25...
I looked up how many X points most people have who are at level 25. It is about 30,000, minimally. Simple math says if I work steadily at about 50 points daily (between 35 and 40 minutes), the quotient is 600. Thus 600 days of actual work. Factoring in some down time, I estimate 2 years. Obviously this reflects a certain level of participation. The person working only 10 points a day might take 10 years. The person earning 100 points a day might be done in 300 days.
And Olimo (below) completed in only 3 months. My guess is (a) she's a hard worker, and (2) she wasn't worried about getting all the way to level 25, which makes perfect sense. BTW she's got an amazing record on Duolingo! I want to follow her. Duoling08 (below) finished all the skills in Spanish in only 25 days, with prior background in Portuguese. So awesome, both of these people!
The deceptive thing for me is that you level up much quicker at the earlier levels. For instance I'm already at level 7 in German, with only 940 points, and VERY rudimentary skills.
Reality check: I'm doing Pimsleur French along with this. I'm about 70% through the 5 levels. I do each 1/2 hour lesson twice, so I've spent about 110-120 hours on them. It helps to have so much high quality speaking practice.
I'm currently at L12 in Duolingo with 4500 X points. My guess is that by this summer (it's Feb now) I will be able to express myself reasonably well when I go to France, but will struggle on the receptive side. If I finish Pimsleur, I may add on Yabla, to boost my listening comprehension.
I suspect it would take me much more than 2 years to do Russian or Chinese or Arabic, and lots of supplemental work to boot, but I'm old. I'll save those for my next life.
Of course the more long-winded I get, the fewer XP I'll earn. Oops.