How to use
- Choose what you want to find.
- Enter the values of A and B.
- The answer appears instantly, along with a sentence explaining it.
Formula
A% of B = A × B ÷ 100
A is what % of B = A ÷ B × 100
% change = (B − A) ÷ A × 100
Tips and common uses
Marks and exam results
To turn marks into a percentage, choose "A is what % of B", enter the marks you got as A and the total marks as B. For 432 out of 500 the answer is 86.4%.
Percentage change is not symmetric
A 20% rise followed by a 20% fall does not bring you back to the start: 100 becomes 120, and 20% off 120 is 96. Always calculate the change from the starting value.
Percentage points vs percent
If an interest rate moves from 8% to 9%, it has risen by 1 percentage point, but the rate itself has increased by 12.5%. Use "change" mode with 8 and 9 to see the difference.
Frequently asked questions
How do I calculate marks percentage?
Choose "A is what % of B", enter your marks as A and the total marks as B. For example, 450 out of 500 is 90%.
How do I find a percentage increase?
Choose "% change from A to B", enter the old value as A and the new value as B. A negative result means a decrease.
Can I use decimals?
Yes, both A and B can be decimals or negative numbers.