Average and Weighted Percentage
When several percentages contribute different amounts to the whole, a weighted average gives the right answer. Defaults: 30 of 150 = 20%.
The simple average of 50% and 100% is 75%, but if 50% is the score on a 90-mark exam and 100% is on a 10-mark quiz, the weighted average is 55%, not 75%. Use the X-is-what-percent calculator above on (total marks scored) ÷ (total marks possible).
Worked examples
45 of 90 + 10 of 10 = 55 of 100 = 55% — weighted exam total.
£200 return on £5k + £300 return on £10k = £500 / £15k = 3.33% — portfolio return.
Frequently asked questions
How is a weighted average different from a simple average?
Simple average treats every value as equal. Weighted average gives more importance to values with bigger weights — e.g. a 60-mark exam counts more than a 10-mark quiz.
Should I weight by absolute value or by share?
Either works as long as you're consistent. Weighting by absolute (e.g. mark count) is usually clearest.