Almost every multiple-choice oposición in Spain deducts points for each mistake. How much is set by each call, and that number drives a decision you make dozens of times during the exam: answer or leave blank. This page has the calculator and the explanation of the formula, with the values that appear in the verified calls for each exam.
Calculator#
Pick your exam or enter your own values. The score is computed as correct answers times the value of each one, minus wrong answers divided by the penalty divisor.
Blank: 60
Result
0 out of 60
0 % of the maximum
correct × 1 − wrong × 1 ÷ 3
The formula boards use#
The most common way to mark an oposiciones test is this:
Score = correct × value of a correct answer − wrong × value of a correct answer ÷ divisor
Blank questions neither add nor subtract. The divisor is the number that appears in the call as "each wrong answer will be penalised with one third (or one quarter) of the value of a correct answer". Voided questions, when there are any, are replaced by the reserve questions in the order they appear.
These are the values in the current calls of the exams most prepared on Oposilab:
| Exam | Multiple-choice exercise | Penalty per mistake |
|---|---|---|
| Auxiliar Administrativo del Estado | 60 questions (30 syllabus and 30 psychometric) and 50 on office software, 90 minutes in total | One third of a correct answer |
| Administrativo del Estado | 70 syllabus and office-software questions, plus a case in 20 questions | One third of a correct answer |
| Auxilio Judicial | 100 theory questions (0.60 points each) and 40 practical ones | One quarter of a correct answer |
| Tramitación Procesal | 100 theory (0.60 points each), 10 on a case and 20 on IT | One quarter of a correct answer |
| Gestión Procesal | 100 theory (0.60 each) and 10 on a case (1.5 each) | One quarter on theory and one fifth on the case |
| Agente de la Hacienda Pública | 80 questions in 90 minutes | One quarter of a correct answer |
| Auxiliar Administrativo, Comunidad de Madrid | 40 organisation questions and 30 on office software | One third of a correct answer |
| Correos | 90 syllabus questions and 10 psychometric | No penalty |
The full structure of each exam, with the source and the date we checked it, is in the "Call and exam" section of each exam page.
When answering a doubtful question pays off#
The penalty is not designed to punish: it is calibrated so that random answering gives no advantage. With four options and a one-third penalty, the expected value of answering with no knowledge is exactly zero: a 0.25 chance of a correct answer worth one point, minus a 0.75 chance of a mistake worth one third of a point. If you can rule out a single option, the expected value turns positive: one third of a correct answer minus two thirds of a mistake divided by three, which is one ninth of a point in your favour.
With a one-quarter penalty, as in Justice and the Tax Agency, random answering among four options already has a positive expected value (0.25 minus 0.75 divided by 4, which is 0.0625). And with no penalty, as in Correos, you must answer absolutely everything.
What expected value does not capture is variance. If you are close to the cut-off and need certainty, leaving blanks reduces risk in exchange for expected points. It is a personal decision worth rehearsing before the exam, not discovering inside it.
How to rehearse the penalty before the exam#
The penalty changes how you review. A mock exam without penalty teaches you to answer everything; one with the real penalty teaches you to decide. That is why Oposilab mock exams replicate the structure of each exam's call: number of questions, reserve questions, time and penalty divisor. When you finish, the result shows how many points you lost to mistakes and how many you left on the table in blank questions you knew, and every question shows the article behind it.
A routine that works:
- Take a mock exam with the real penalty every week during the last month.
- Write down, besides the score, how many doubts you resolved right and how many wrong.
- If your doubts hit above 33% (with one third) or above 25% (with one quarter), answer more; if they fall below, leave more blank.
- Do blank questions subtract points?
- Not in the verified calls on this page. Only mistakes subtract. Always check the marking section of your call, because that is what the board will apply.
- What happens with voided questions?
- Calls include reserve questions. If the board voids a question, it replaces it with the first reserve question in order, and so on. That is why it pays to answer the reserve questions too.
- Does the calculator give the cut-off score?
- No. The cut-off depends on the call, the number of places and the results of the other candidates. The calculator only applies the marking formula to your correct and wrong answers.
- Does this calculator work for any exam?
- Yes. In custom mode you can enter the number of questions, the value of a correct answer and the penalty divisor of any call.
