A UPSC prelims marks calculator credits 2 marks per correct answer in GS Paper I and takes off one third of that, about 0.66, for each wrong answer, so 64 right and 21 wrong give 128 minus 14, which is 114 out of 200. In CSAT each question is worth 2.5 marks and a wrong answer costs about 0.83.
CSAT is qualifying: you need at least 66 out of 200 (33 percent), and only then is your GS Paper I score used for the cut-off. Enter your counts from the official answer key into the calculator above. UPSC alone decides the cut-off and the result.
At a glance
GS Paper I
100 questions x 2 marks = 200, 2 hoursGS penalty
One third of 2 = 0.66 per wrong answerCSAT (Paper II)
80 questions x 2.5 marks = 200, 2 hoursCSAT penalty
One third of 2.5 = 0.83 per wrong answerCSAT qualifying
66 out of 200 (33 percent)Blank answer
No penaltyOfficial source
GS = 2 x right - (2/3) x wrong; CSAT = 2.5 x right - (2.5/3) x wrong
The penalty in each paper is one third of the marks for that question. Blank answers are not penalised. More than one answer to a question counts as wrong.
How the UPSC prelims marks calculator above works
Type the number of right and wrong answers for GS Paper I, then for CSAT. The tool works out blanks, applies the one third penalty for each paper and shows GS marks out of 200, CSAT marks out of 200 and whether CSAT has crossed 66.
You can use it to convert IAS prelims answers into marks as soon as unofficial keys appear, then again when UPSC releases its own key. The UPSC CSE marks calculator logic is the same both times; only the key changes.
- Get the answer key for your question booklet series.
- Mark each GS question right, wrong or blank.
- Enter the GS counts; the calculator gives marks out of 200.
- Repeat for CSAT with its 80 questions.
- Check that CSAT is 66 or more.
- If it is, compare your GS marks with past cut-offs published by UPSC.
The two papers and their marking
| Paper | Questions | Marks each | Penalty per wrong | Max | Role |
|---|---|---|---|---|---|
| GS Paper I | 100 | 2 | 0.66 (2/3) | 200 | Decides the merit cut-off |
| CSAT (GS Paper II) | 80 | 2.5 | 0.83 (2.5/3) | 200 | Qualifying, 66 needed |
Both papers are objective and 2 hours long. The notice says one third of the marks assigned to a question is deducted for a wrong answer. It also says that giving more than one answer is treated as wrong, even if one of them is right.
Worked example for GS Paper I
Right 64, wrong 21, blank 15 (total 100).
Marks = 64 x 2 - 21 x 2/3 = 128 - 14 = 114 out of 200.
If you use 0.66 instead of 2/3 you get 128 - 13.86 = 114.14. The gap is small here, but it grows with more wrong answers, so the calculator uses the exact one third.
| Correct | Wrong | Blank | GS Paper I marks |
|---|---|---|---|
| 90 | 6 | 4 | 176 |
| 80 | 12 | 8 | 152 |
| 75 | 15 | 10 | 140 |
| 70 | 18 | 12 | 128 |
| 65 | 21 | 14 | 116 |
| 60 | 24 | 16 | 104 |
| 55 | 27 | 18 | 92 |
| 50 | 30 | 20 | 80 |
| 45 | 30 | 25 | 70 |
| 40 | 30 | 30 | 60 |
CSAT marks calculator: will you clear 66?
Right 34, wrong 12. Marks = 34 x 2.5 - 12 x 2.5/3 = 85 - 10 = 75. That is above 66, so CSAT is cleared.
Right 30, wrong 15. Marks = 75 - 12.5 = 62.5. That is below 66, so GS marks will not be considered, however high they are.
| Correct | Wrong | CSAT marks | Reaches 66? |
|---|---|---|---|
| 40 | 6 | 95 | Yes |
| 36 | 9 | 82.5 | Yes |
| 34 | 12 | 75 | Yes |
| 32 | 6 | 75 | Yes |
| 30 | 15 | 62.5 | No |
| 30 | 6 | 70 | Yes |
| 28 | 3 | 67.5 | Yes |
| 27 | 0 | 67.5 | Yes |
| 26 | 0 | 65 | No |
Notice the last rows: with no wrong answers, 27 right (67.5) clears the line and 26 right (65) does not.
Why guessing at random does not pay
Each question has four options. A pure guess is right one time in four. In GS that gives an average of 0.25 x 2 = 0.5 gained and 0.75 x 0.667 = 0.5 lost, which is zero. In CSAT it is 0.625 gained and 0.625 lost, also zero. So blind guessing neither helps nor hurts on average, but it widens the spread of your score. Guessing after you have ruled out one or two options is a different matter, because the odds move in your favour.
Common mistakes with UPSC marks
| Common error | Why the score goes off | Correction |
|---|---|---|
| Using 0.66 x wrong for large counts | The penalty is exactly one third of 2, so 30 wrong cost 20, not 19.8 | Use 2/3 or let the calculator do it |
| Same penalty in CSAT as in GS | CSAT questions carry 2.5 marks, so a wrong one costs 0.83, not 0.66 | Score the two papers separately |
| Counting a double marked answer as blank | More than one answer to a question is treated as wrong | Put it in the wrong column |
| Adding CSAT to the GS total | CSAT is only qualifying; merit uses GS Paper I | Check CSAT against 66, then use GS marks alone |
| Thinking prelims marks reach the final list | Prelims marks do not count in the final merit | Treat prelims as a screening step |
Where to find your answers and the key
Prelims is an OMR paper, so the safest record of your answers is the one you note on the question booklet while you fill the sheet. Use the key that matches your booklet series. UPSC puts out its own key only later in the process; until then any key you use is unofficial, so treat your score as an estimate.
Other exams use their own rules. The UPSC CMS marks calculator, CDS and EPFO tests, and state PSC prelims each have their own notice, so do not reuse these penalties without checking. For a general one third penalty paper, the negative marking calculator lets you set the values. For central recruitment tests see the SSC CGL marks calculator and the SSC marks calculator, and for postgraduate technical exams the GATE marks calculator.
Questions students ask
How many marks are deducted for a wrong answer in UPSC prelims?
One third of the marks for that question. That is 0.66 in GS Paper I, where each question is worth 2, and 0.83 in CSAT, where each is worth 2.5.
Is CSAT counted in the UPSC prelims cut-off?
No. CSAT is qualifying only. You need 66 out of 200, and then the cut-off is applied to GS Paper I marks alone.
How do I use the UPSC pre marks calculator with an answer key?
Compare each of your answers with the key for your booklet series, sort them into right, wrong and blank, and enter the counts for each paper. The calculator handles the penalty.
Is a blank answer penalised in UPSC prelims?
No. Only wrong answers lose marks. Marking more than one option for a question counts as a wrong answer.
Do prelims marks count in the final UPSC merit list?
No. Prelims is a screening test. The final merit is based on later stages.
Is it fine to run only the GS part in this UPSC GS marks calculator?
Yes. Enter only the GS counts to see GS marks. Remember that CSAT must also reach 66 for the GS marks to matter.