How much time does it take to improve your TOEIC score? Well, it depends.
Look at the chart below. It shows that if you are starting with a score of 500, you would need 250 hrs to get to 600 points, or 550 hrs to get to 700 points, or 1300 hours total to get to 900 points.
If you are starting from a very low level, you can improve your score by 100 points relatively quickly. Any new word or grammar point you learn can make a big difference in your score. However, when you have a higher level, it takes considerably more hours to improve your TOEIC score. If you look at the chart, you’ll see that if you start with a score of 200, it would take 100 hours of studying to increase your score to 300. 100 hrs of study = +100 TOEIC score. Not too bad. However, if you start at 800 points, you’ll need 400 hours of study to increase your score to 900. At this level 400 hours of study = +100 TOEIC score.
The following chart shows how when you are the lower TOEIC levels, you can get an extra point (eg. improve your score from 250 to 251) with only 1 hour of study. However if you have a score of 850 in TOEIC, you would need to study for 4 hours to bring your score up to 851.
This is true for all tests as it is true for learning languages. You can improve very quickly at the beginning, but becoming fluent requires time, effort, and lifestyle changes.