Percentage Calculator
Four everyday percentage calculations in one place, each with the formula shown so you can check the working.
All calculations run in your browser. The numbers you enter are not sent or stored anywhere. Privacy policy
How to use the Percentage Calculator
- 1Choose the type of calculation.
- 2Enter the two numbers.
- 3The answer and formula appear instantly.
Supported formats and limits
- Works with decimals and negative numbers where they make sense.
Formulas used
X% of Y = X ÷ 100 × Y.
A is what % of B = A ÷ B × 100. This is also how marks percentage is calculated: marks obtained ÷ total marks × 100.
Percentage change from A to B = (B − A) ÷ |A| × 100. A positive result is an increase, a negative result a decrease.
Some universities convert CGPA to percentage with their own formula; use your university's official rule for that.
Frequently asked questions
How do I calculate marks percentage?
Choose "A is what % of B", enter your total marks obtained as A and the maximum marks as B.
Is a 50% increase followed by a 50% decrease back to the start?
No. 100 increased by 50% is 150; 150 decreased by 50% is 75. Percentages apply to the current value each time.