How to Convert Marks to a Percentage
3 min read · Last reviewed July 1, 2026
Whether you're filling in a university application, comparing results across subjects, or just curious how you did, converting marks to a percentage is one of the most common bits of maths students need. It's also one of the simplest.
This guide gives you the one formula that covers it, then shows how to handle the two situations that trip people up: several subjects at once, and papers that aren't worth the same.
The basic formula
To turn marks into a percentage, divide the marks you scored by the total possible marks, then multiply by 100. So 68 out of 80 is (68 ÷ 80) × 100 = 85%.
That's it — the whole thing hinges on getting the total right. The 'total' is the maximum available on that paper or subject, not the pass mark and not the class average.
Combining several subjects
For an overall percentage across subjects, add up all the marks you scored, add up all the totals, then apply the same formula. If you scored 68, 74, and 59 on three papers each out of 80, that's 201 out of 240, which is (201 ÷ 240) × 100 = 83.75%.
A common mistake is to work out each subject's percentage and then average those percentages. That only gives the right answer when every subject is out of the same total. When totals differ, always add the raw marks first.
When papers carry different weights
Sometimes a coursework mark counts for, say, 40% of a subject and the exam for 60%. In that case multiply each component's percentage by its weight and add them. A coursework score of 70% weighted 40% plus an exam of 80% weighted 60% gives (70 × 0.4) + (80 × 0.6) = 28 + 48 = 76%.
For rounding, one decimal place is usually plenty. Check whether your institution rounds up at 0.5 or uses standard rounding, as it can occasionally nudge you into the next grade band.
Frequently asked questions
▶How do I calculate the percentage of total marks?
Divide your total marks scored by the total marks available, then multiply by 100. For 450 out of 500, that's (450 ÷ 500) × 100 = 90%.
▶Can I just average the percentages of each subject?
Only if every subject is out of the same total. If the totals differ, add up all the raw marks and all the totals first, then convert — otherwise the result is skewed.
Try the calculators
Convert your exam marks into a percentage — enter marks obtained and total marks to get your result and grade.
Open calculator →Work out a percentage of a number, what percent one number is of another, and percentage increase or decrease.
Open calculator →Calculate your grade point average on the 4.0 scale from your course grades and credit hours.
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