The structure of the PSAT mirrors that of the SAT with four test sections with varying numbers of questions per section. Test takers receive a raw score for each section based entirely on the number of questions answered correctly. Then, raw scores are used to produce scaled scores.
However, the PSAT score scales differs from that of the SAT. While the questions themselves are the same, each version of the PSAT includes fewer questions per section than the SAT, which leads to lower maximum scores.
Based on their raw scores on the PSAT Reading and Writing and Language sections, test takers receive scaled scores of 8–38 for each section. These scaled scores are added, then the sum is multiplied by 10 to produce the 160–760 Evidence-Based Reading and Writing Section score.
The raw scores for the Math – No Calculator and Math – Calculator sections are added, then scaled to produce the 160–760 Math score.
The 160–760 Evidence-Based Reading and Writing Section and 200–800 Math scores are added to produce the 320–1520 Total PSAT score, which is the same for the PSAT/NMSQT and PSAT 10. The PSAT/NMSQT score report also lists test scores of 8-38 for Math, Reading, and Writing and Language, which matter, and a variety of subscores and cross test scores, which really don’t..
PSAT 8/9 scores are lower still, with 120–720 Evidence-Based Reading and Writing Section and Math scores adding up to a 240–1440 Total PSAT 8/9 score
Note that the National Merit Scholarship Selection Index is calculated in a different way than the PSAT Total Score.
College Board page on PSAT scoring
College Board page on PSAT 8/9 scoring
Sample PSAT/NMSQT Score Report 2018
What is the PSAT?
How does the National Merit Scholarship process work?
How is the National Merit Scholarship Selection Index calculated??