Should you guess on the IMAT? The maths behind it
Pure guessing between five options is very slightly negative, so it is close to a coin flip you can skip. But the moment you can rule out even one option, answering becomes clearly worth it — and with two eliminated it is strongly worth it. The skill to train is not guessing; it is noticing when you can eliminate.
Almost every IMAT candidate asks this at some point, usually the night before: if I have no idea, should I tick something anyway?
The honest answer is that it depends on one thing only — whether you can eliminate an option. And you can work out exactly where the line sits.
The rule that makes this a real question
The IMAT has historically used an asymmetric marking scheme: a correct answer earns marks, a wrong answer costs a fraction of a mark, and an unanswered question costs nothing.
Confirm the exact figures for your exam year against the official sources at the end of this guide. The reasoning below holds for any scheme where a wrong answer costs less than a right one earns.
Working with the figures that have applied in recent years — +1.5 for a correct answer, −0.4 for a wrong one, 0 for a blank — the question becomes arithmetic rather than nerve.
The expected value of answering
Expected value means: if you faced this same situation a hundred times, what would you gain per attempt on average?
| Options you cannot rule out | Chance of hitting it | Expected value per guess |
|---|---|---|
| 5 (no idea at all) | 20 % | −0.02 |
| 4 (one eliminated) | 25 % | +0.08 |
| 3 (two eliminated) | 33 % | +0.23 |
| 2 (three eliminated) | 50 % | +0.55 |
The first row is the surprise for most people: blind guessing is not a disaster. It is very slightly negative — essentially neutral. Across ten blind guesses you would expect to lose about two tenths of a mark.
The second row is the one that matters: eliminating a single option flips the sign. From there, answering is always the better play.
What this means in the exam
Never leave a question blank if you can rule out even one option. Most candidates are far too cautious here. If a chemistry option contradicts a rule you know, or a biology option describes a process that does not exist, you have already earned the right to answer.
Blind guessing is not the sin it is made out to be — but it is also not a strategy. If you find yourself blind-guessing on many questions, that is a coverage problem. No amount of exam-day tactics fixes a topic you never studied.
Watch the clock instead. A blank left because you ran out of time is the worst outcome of all: it costs you the guess and the chance to eliminate. Reaching the end of the paper matters more than perfecting the middle of it.
The habit worth building
When you practise, mark every question where you guessed, and note how many options you had actually ruled out. Two things usually surface:
- Your “pure guesses” often are not pure — you eliminated something without registering it, which means you should have answered with more confidence.
- Your accuracy on guessed questions is lower than it feels. That gap is cheaper to discover now than on exam day.
Elimination is a trainable skill and it compounds: knowing why a wrong option is wrong is exactly the knowledge that later makes the right one obvious.
The short version
Ruled out nothing? Answering is roughly neutral — decide by time, not by hope. Ruled out one or more? Answer. Every time.
Sources
Exam rules and dates change. Always confirm the details that matter for your application against the official sources above.
Or keep going in the iPhone app.
Found a mistake? Write to hello@imatlearn.com — corrections are made at the source.