Negative Marking: When Is It Worth Guessing?

2026-10-18 · 6 min read

Under negative marking, every guess is a small bet. Whether the bet is worth taking is simple arithmetic - and the answer is different for different exams.

The rule

Suppose a right answer gets R marks and a wrong one loses W. If your chance of being right is p, a guess is worth, on average:

p × R − (1 − p) × W

It pays when that is more than zero, which is when p is more than W ÷ (R + W). That fraction is the break-even chance.

Pure guesses

If you have no idea at all and pick at random, p is 1 divided by the number of options. Worked out from each exam's official marking (as used in our mock tests):

JEE Main, NEET, IISER IAT (+4, −1, four options): break-even 20%; a pure guess is right 25% of the time, worth +0.25 marks on average.
CUET General Test (+5, −1, four options): break-even about 17%; a pure guess is worth +0.5 marks.
SSC CGL Tier 1 (+2, −0.5) and CLAT, CA Foundation Paper 3 (+1, −0.25), four options: break-even 20%; a pure guess is worth a little more than nothing (+0.125 and +0.06 marks).
IBPS PO Prelims (a quarter of the marks lost, five options): break-even 20%, and a pure guess is right exactly 20% of the time, so on average it gains nothing.
CAT, JEE Advanced single-answer, UPSC Prelims, NDA, GATE multiple choice (a wrong answer costs a third of a right one, four options): break-even 25%, and a pure guess is right exactly 25% of the time - on average it gains nothing.

On average is the key phrase: a handful of pure guesses can easily lose you marks in one sitting. Where the expected gain is nothing, guessing only adds risk.

Rule out one option and everything changes

Eliminate just one wrong option and p rises from 25% to 33% (or from 20% to 25% with five options). That is above the break-even in every exam above:

CAT: a guess between three options is worth +0.33 marks.
GATE: +0.11 on a 1-mark question, +0.22 on a 2-mark question.
UPSC GS Paper 1: +0.22 marks.
IBPS PO: small, but positive.

Rule out two, and it is a coin toss - clearly worth it in every one of these exams.

No negative marking? Always answer

Some questions carry no penalty: CAT's type-in-the-answer (TITA) questions, GATE's multiple-select and numerical questions, and JEE Advanced's numerical questions. Never leave these blank if you have time to enter something sensible.

Three things the maths leaves out

Time. A guess costs seconds; a question you wrestle with for five minutes costs marks elsewhere. Guess quickly or skip quickly.
Qualifying papers. UPSC's CSAT only needs 33% to qualify. The aim is to clear that mark safely, not to maximise the score, so avoid needless risks once you are comfortably above it.
Confidence is not accuracy. Most of us are overconfident. Your mock test report shows your real accuracy on the questions you attempted; if it is low, your "educated guesses" may be closer to pure guesses than they feel.

Practise the habit: in your next mock test, mark each guess for review, and count afterwards how many came off.