Cambridge guided learning hours
Cambridge English publishes the hours of guided learning a typical learner needs for each level, counted from zero: about 90–100 hours for A1, 180–200 hours for A2, 350–400 hours for B1 and 500–600 hours for B2. They describe focused course time and were written for learners of English, and Cambridge itself notes that language background and study intensity change the picture.
Cambridge English: guided learning hours ↗