Your IELTS Reading scores are calculated by the number of correct answers you have out of 40 questions in the test. You get one mark for each correct answer in the IELTS Reading test. The total correct answers will determine your 'raw' score from which your band score will be determined. It's very important to try and answer every question as a blank answer will get no marks.
Your IELTS Reading band score contributes to your overall IELTS band score.