How to Calculate Percentage From Marks

Converting marks to percentage is a simple ratio calculation. The same basic method works for a quiz out of 20, an exam out of 100, a 500-mark school total or a 600-mark subject set.

The formula

Percentage = (marks obtained ÷ maximum marks) × 100

The maximum marks are the marks the assessment or group of assessments could have earned. Use the correct denominator before doing the calculation.

Worked examples

42 out of 60: 42 ÷ 60 × 100 = 70%.

425 out of 500: 425 ÷ 500 × 100 = 85%.

512 out of 600: 512 ÷ 600 × 100 = 85.33%.

18 out of 20: 18 ÷ 20 × 100 = 90%.

How to calculate an overall percentage

Add all the marks you earned. Then add all the maximum marks. Finally use the formula above. This matters when subjects have different totals.

Why averaging subject percentages can be wrong

Imagine one paper is out of 50 and another is out of 100. Averaging their percentages gives each paper the same weight even though the second paper has twice the maximum marks. If the official result is based on raw marks, combine the marks first.

Rounding

Keep the full value during the calculation and round the final percentage to the number of decimal places your school or university uses. Early rounding can create small differences.

Common mistakes

Using 100 as the denominator for a paper that is not out of 100.
Forgetting to include a component that officially counts.
Averaging percentages when maximum marks are different.
Confusing percentage with percentile.

Calculate it online

Use the Marks to Percentage Calculator for a quick result, or the Percentage Calculator for other percentage questions.