Negative marking: when does guessing pay? SSC, bank, railway, UPSC and CAT
"Should I guess?" is one of the most common questions before any objective exam. The usual answers ("never guess" or "always guess") are both wrong. The right answer depends on two numbers printed in the notice: the marks for a right answer and the penalty for a wrong one. This article gives the rule and works it out for the major Indian exams.
The rule in one line
A guess is worth it when your chance of being right is higher than:
penalty ÷ (marks for a right answer + penalty)
Call this the break-even chance. Below it, guessing loses marks on average. Above it, guessing gains marks on average.
Why? If your chance of being right is p, a guess earns p × marks and costs (1 − p) × penalty on average. The two are equal exactly at the break-even chance.
The break-even chance in each exam
| Exam | Right answer | Wrong answer | Break-even chance |
|---|---|---|---|
| SSC CGL Tier-I | +2 | −0.5 | 20% |
| SSC CGL Tier-II, SSC CHSL Tier-II | +3 | −1 | 25% |
| IBPS PO prelims, SBI PO prelims | +1 | −0.25 | 20% |
| RRB NTPC CBT-1 | +1 | −1/3 | 25% |
| UPSC prelims GS Paper I | +2 | −2/3 | 25% |
| CAT, multiple-choice questions | +3 | −1 | 25% |
| CAT, typed answers | +3 | 0 | 0%: always answer |
The marks are those in each exam's current notice, as summarised on our pages for SSC CGL, IBPS PO, SBI PO, RRB NTPC, UPSC CSE and CAT. Always check the notice for your own year, because marking does change.
What "chance of being right" means in practice
With four options and no idea at all, your chance is 25%. Every option you can confidently rule out raises it:
| Options left | Chance of being right |
|---|---|
| 4 (no idea) | 25% |
| 3 (one ruled out) | 33% |
| 2 (two ruled out) | 50% |
Banking exams use five options, so a blind guess there is 20%, then 25%, 33% and 50% as you rule options out.
So when should you guess?
SSC CGL Tier-I (+2, −0.5): the break-even chance is only 20%, so even a blind guess between four options gains a little on average: +0.125 marks per question. Rule out one option and a guess is worth +0.33 marks on average; rule out two and it is worth +0.75. In this exam a guess after ruling out even one option is clearly worth it.
SSC CGL Tier-II and CHSL Tier-II (+3, −1): the break-even chance is 25%, so a blind guess between four options gains nothing on average and only adds risk. Rule out one option first; after that a guess gains +0.33 on average.
IBPS PO and SBI PO prelims (+1, −0.25, five options): a blind guess is exactly at break-even. Rule out one option and it turns positive. Keep in mind that IBPS also has a cut-off in each section, so a few careless guesses in a weak section can matter more than the average suggests. SBI PO prelims has no sectional cut-off.
RRB NTPC CBT-1 (+1, −1/3): break-even is 25%. With four options, a blind guess gains nothing on average; one option ruled out makes it worth it.
UPSC prelims GS Paper I (+2, −2/3): break-even is again 25%. Prelims toppers often attempt more questions than the safe minimum precisely because, after ruling out one or two options, the odds favour them. CSAT (Paper II) is qualifying at 66 marks out of 200, so there the aim is only to pass it safely.
CAT: for multiple-choice questions, break-even is 25%. For typed answers there is no penalty at all, so never leave a typed answer blank if you have any number in mind.
Three cautions
- The average is not the whole story. A guess that gains on average can still lose on the day. If you need a safe score to clear a sectional cut-off, be stricter in that section.
- Time matters more than the guess. Do not spend two minutes ruling out options. The rule applies to questions you have already read and cannot finish; a quick, informed guess then is fine, a long struggle is not.
- Your "ruled out" must be real. If you often rule out the right answer, your real chance is lower than the table says. Your mock results show this: check how often your educated guesses were right.
Test it on yourself
The best way to set your own guessing rule is to track it in mocks. Mark the questions you guessed, then see how many of them you got right. If your educated guesses are right more often than the break-even chance, keep guessing that way; if not, guess less.
You can sit timed mocks with the real marking for SSC CGL, IBPS PO, RRB NTPC and many more on Mockrooms, and every result shows how many marks your wrong answers cost you.