The Common European Framework of Reference for Languages (CEFR) is used to classify language learners’ performance according to six levels ranging from A1 (beginner) to C2 (proficiency), but is it possible to quantify the number of hours required?
Generally, it is recommended that learners spend about 200 hours in order to progress from one CEFR level to the next (see e.g. Cambridge). Not within your budget? Don’t worry – the number depends on individual circumstances and includes self-study and exposure to the language outside of the classroom; it does not mean that you need 200 hours of trainer-centred tuition.
When learning English, I find that it is usually the case that learners progress more quickly through the lower levels, while moving from C1 to C2 can be a more drawn out affair. Using basic vocabulary and structures is not really that complicated in Engish, while understanding and using phrasal verbs is a challenge to the vast majority of trainees.