Count the number of correct, incorrect and omitted responses for each section -- math, writing and critical reading.
Score one point for every correct response for each section.
Deduct 0.25 point for each incorrect answer as a guessing penalty, and don't add or subtract points for omitted responses. For example, the writing section has 39 questions. You will earn 33.25 points if you have 34 correct, 2 omitted and 3 incorrect answers. The math section, however, features a 10-question free response segment that has no guessing penalty.
Round the total to the nearest whole number. The rounded number is your raw score.
Convert your raw score to a scaled score, which ranges from 20 to 80 points. When you purchase an old exam, you will also get a conversion table. Each individual test has its own conversion table, and the scaled score is adjacent to the raw score on the conversion table.
Add the three scaled scores to calculate your overall PSAT score, which ranges from 60 to 240 points.