# How is the National Merit Selection Index calculated?

Source: https://1600.now/sat-faq/how-is-the-national-merit-selection-index-calculated

---

PSAT and National Merit

Double your PSAT/NMSQT Reading and Writing score, add Math, then divide by 10. The Selection Index ranges from 48 to 228 because each PSAT/NMSQT section ranges from 160 to 760.

Written by [Luke Finigan](https://1600.now/about)

2 min read Updated Oct 2, 2026

### The formula, with an example

Let $R$ be Reading and Writing and $M$ be Math. Then $SI=(2R+M)/10$. For $R=720$ and $M=710$, compute $2(720)=1440$, then $1440+710=2150$, then $2150/10=215$.

Use section scores, not your total score or a percentile. The formula here is for PSAT/NMSQT screening; do not enter SAT section scores and call the result your qualifying PSAT index.

| Reading and Writing | Math | Total | Selection Index |
| --- | --- | --- | --- |
| 720 | 710 | 1430 | 215 |
| 710 | 720 | 1430 | 214 |
| 760 | 760 | 1520 | 228 |
| 160 | 160 | 320 | 48 |

### Why Reading and Writing matters twice

A ten-point Reading and Writing increase adds two index points. A ten-point Math increase adds one. If two students have the same total, the one with the higher Reading and Writing score has the higher index.

That weighting does not change the SAT total-score formula. SAT section scores still add once each. It also does not remove Math from National Merit preparation; your next practice priority depends on what you can actually learn.

### Compare against the right cutoff

Use the index shown on your score report as the official reference. Then check the [cutoffs by graduation class and state](https://1600.now/psat-national-merit-cutoffs) and your program eligibility. Reaching a listed number is not the same as receiving a scholarship.

### Sources and current rules

- [College Board: understanding score reports](https://satsuite.collegeboard.org/scores/what-scores-mean)
- [College Board: National Merit Scholarship Program](https://satsuite.collegeboard.org/in-school-assessments/scholarships-recognition/national-merit-scholarship-program)

### Related SAT answers

- **[What PSAT score qualifies for National Merit?](https://1600.now/sat-faq/what-psat-score-qualifies-for-national-merit)**

  National Merit screening uses your PSAT/NMSQT Selection Index, not one nationwide total-score cutoff. Semifinalist qualifying scores vary by state or selection unit and graduation class; eligibility requirements and later application steps also matter.
- **[PSAT vs SAT: What is the difference?](https://1600.now/sat-faq/psat-vs-sat)**

  The PSAT/NMSQT and SAT test related skills in the same standard digital timing: 2 hours 14 minutes plus a break. The PSAT/NMSQT tops out at 1520 and can qualify eligible students for National Merit; the SAT tops out at 1600 and is used in college admissions.

[Browse SAT resources →](https://1600.now/sat-resources)