The basic formula
Add the marks you earned, add the maximum marks available, then divide the first total by the second and multiply by 100. In symbols: percentage = (marks obtained ÷ maximum marks) × 100. Keep the numerator and denominator in the same unit; do not divide by the number of subjects unless you are calculating an average score for a specific reason.
For example, if you score 432 out of 500, calculate 432 ÷ 500 = 0.864. Multiply 0.864 by 100 and the result is 86.4%. The percentage is not 432 divided by 5 by coincidence; it follows from the total available marks being 500.
Subject scores: 82/100, 76/100, 91/100, 88/100 and 95/100.
Obtained = 82 + 76 + 91 + 88 + 95 = 432. Maximum = 500.
(432 ÷ 500) × 100 = 86.4%
When subjects have different maximum marks
Use the combined marks, not an unweighted average of subject percentages, when the official result is based on a combined total. Imagine one subject is out of 50 and another is out of 100. A score of 40/50 is 80%, while 70/100 is 70%. Their combined score is 110/150 = 73.33%, not the simple average of 80% and 70% (75%). The combined total gives each available mark the weighting defined by the exam.
If your board or institution publishes a result formula, follow that formula. Practical work, internal assessment, optional subjects, language papers and best-of-subject rules can change the official denominator.
How to calculate a target score
You can rearrange the same formula to estimate the marks needed for a target percentage. Required marks = target percentage ÷ 100 × maximum marks. For an 80% target on a 500-mark exam, the calculation is 0.80 × 500 = 400 marks. This is a planning estimate, not a prediction of the final result.
For a subject-wise target, calculate each subject separately and leave a small buffer. A plan that targets exactly the threshold can fail if one paper is harder than expected or a component is counted differently.
Target: 90% of 600 marks.
0.90 × 600 = 540 marks
A useful study plan then breaks the 540-mark goal into subject targets based on strengths and exam weightings.
Common mistakes to avoid
Do not add percentages together and label the sum as the final percentage. Do not divide by the number of subjects if maximum marks differ. Check whether a subject is out of 80, 70, 50 or another value. Confirm whether the result includes practicals and internal assessment. Finally, keep the precision that the official rules require; rounding 86.45% to 86% may be inappropriate if the institution expects two decimal places.
Use a calculator to reduce arithmetic slips, then compare the inputs with the official mark sheet. A calculator can only be as reliable as the numbers and rules you enter.
A simple result-checking workflow
First, copy each obtained mark and maximum mark from the source document. Second, verify that you included exactly the subjects used by the board. Third, calculate the total and percentage. Fourth, compare the output with any result portal or marks memo that provides an official percentage. If the two values differ, investigate the denominator or rounding rule instead of repeatedly recalculating the same inputs.
When sharing a result online, avoid posting your roll number, date of birth, registration number or other identifiers. A percentage is usually enough for general discussion.