How many questions should you attempt in UPSC Prelims? Find your own threshold
There is no safe number of attempts in UPSC Prelims. Tag each mock answer as Sure, Down to two or Guessing, find your accuracy in each, and attempt every kind that is right more than 25% of the time. Your number of attempts follows from that.
Keshav Melnad · Updated
Prelims strategy6 min read
Ask anyone how many questions to attempt in GS Paper I and you will get a number. One popular page says most experts suggest 80 to 85 out of 100 "if your accuracy is decent", and up to 90 if you are confident. Other pages give other ranges, but the idea is the same: fix a target and reach it.
I think this is the wrong way round. The number of attempts is not something you should decide before the paper. It is the result of one decision you make again and again inside the paper: "Do I mark this one or not?" Get that decision right and the count takes care of itself.
This post shows how to find your own rule for that decision from your own mocks. It needs only a pencil and the marking scheme.
The marks behind every attempt
GS Paper I has 100 questions for 200 marks, with four options each. A wrong answer loses one-third of the question's marks, and a blank loses nothing. So every question gives you +2 if right, −0.67 if wrong and 0 if left blank. This is printed in the instructions on UPSC's question paper for 2025.
In my post on negative marking I worked out what this means for one question: answering is worth it only when your chance of being right is more than 25%. Below that, a blank is better. That one number is all the theory you need here.
If you are right a fraction p of the time on some kind of question, each attempt of that kind is worth, on average:
2p − ⅔(1 − p) marks
At 25% this is exactly zero. At 50% it is +0.67. At 90% it is +1.73.
Why a target number misleads
Suppose your overall accuracy in mocks is 65%. A target like 85 looks safe, because 65% is far above 25%.
But your 65% is an average. It mixes the questions you knew cold with the ones you half-knew and the ones you marked out of hope. When you push your attempts from 70 to 85, the extra 15 questions do not come from your average. They come from the bottom: the ones you were least sure about. Those 15 might be right only one time in five, and then every one of them loses marks.
So the useful question is not "What is my accuracy?" It is "What is my accuracy on the questions I am least sure about?" Your average cannot tell you that. Your mocks can, if you record one extra thing.
Keshav Melnad
Prepared for the UPSC Civil Services Examination for six years before building CollectorX on his own. He holds a PhD from IIT Bombay, and his research on Sanskrit astronomical texts is published in peer-reviewed journals.
In your next five mocks, or five full PYQ papers, do this for every question you mark:
Before you see the answer, put a small tag next to it: S if you are sure, T if you are down to two options, G if you are guessing.
Tag honestly. "Down to two" means you have really cut two options, not that two options look familiar.
After the mock, count for each tag: how many you attempted and how many were right.
Work out the marks per attempt for each tag with the formula above.
Then the rule is simple. Attempt every tag that is right more than 25% of the time. Skip the first tag that is not. The number of questions you end up marking is your threshold for that paper.
A worked example
Here is how the count might look for one aspirant over five mocks, 500 questions in all. These numbers are an example to show the working, not data from any real person:
Marks per attempt for each tag in the worked example. Only the guesses fall below zero.
This aspirant attempts 93 questions a paper on average, with 65% accuracy overall. By the usual advice, that looks fine.
The tags tell a different story. The Sure and Down-to-two answers both earn marks, so they should keep attempting those. The guesses are right only 21% of the time, below the 25% line, so each one loses a little. Their rule is: attempt when down to two, skip when guessing. Following it, they would attempt about 74 questions a paper, not 93, and score about 2 marks more per paper.
Two marks is not much. But notice what the count changed. The aspirant was not wrong to attempt a lot; most of their attempts were earning marks. They were wrong only about one kind of attempt. And if their guesses had been right 30% of the time, the same method would have told them to keep guessing.
Your number moves with the paper
This is why a fixed target is risky. In a hard paper, fewer questions feel Sure and more feel like guesses. The rule stays the same, but the count drops, maybe to 65. In an easy paper it may rise to 90.
If you walk in with 85 as your target, a hard paper pushes you to fill the gap with guesses, which is exactly where you lose marks. If you walk in with a rule, you do not need to count at all. You only ask, for each question, which tag it would get.
Where this method can mislead you
Small counts. A tag with 12 answers can move by 8 points if one answer goes the other way. Ten answers in a tag is the bare minimum; more is better. Keep adding mocks before you trust a tag that sits close to 25%.
Dishonest tags. If you tag a guess as Down to two because it feels better, the method will give you the wrong rule. The tag must be what you felt when you marked it, not what you wish you had felt.
Subjects differ. Your Down-to-two in polity may be right 60% of the time and in environment only 35%. Once you have enough answers, split the count by subject.
A mock is not the exam hall. Nerves and the last half-hour change how you decide. Your mock numbers are the best guide you have, but treat them as a guide.
Averages, not promises. The rule gives you the most marks on average. It does not know where the cut-off will fall this year, and on one paper luck can still go either way.
How I built this into CollectorX
I built this exact count into CollectorX. In Practice mode in Solo Learn, and in the full Prelims paper, you can tag each answer as Sure, Down to two or Guessing. Once a tag has at least 10 answers, the coaching page works out your accuracy and marks per attempt for it and gives you one rule, such as "Attempt when you're down to two". The rule is free; with Pro you also see the numbers for every tag and how many marks your current habit costs you. Tagging is never required, and duels have no tags. If you would rather do it on paper, the pencil method above works just as well.
CollectorX coaching — CollectorX offers optional Sure / Down to two / Guessing tags in Practice and the Prelims paper; the coaching page shows a tag's numbers after 10 answers and gives one attempt rule free, with per-tag numbers and the cost of habit for Pro. (accessed 7 November 2026)
