What is a percentage calculator, and who needs it?
This calculator answers the three percentage questions people ask most often. "X% of Y" finds a share of a number, such as a discount. "X is what % of Y" turns one number into a percentage of another, such as marks out of a total. "% Increase/Decrease" shows how much a value has risen or fallen between two numbers.
Students use it for marks, shoppers for sale prices, employees for salary hikes and business owners for profit as a share of sales. If you need CGPA rather than a simple percentage, try our CGPA Calculator.
Formula used
- X% of Y = (X ÷ 100) × Y
- X is what % of Y = (X ÷ Y) × 100
- Percentage change = (To − From) ÷ From × 100
- A positive change is shown as an increase and a negative change as a decrease
- All results are rounded to two decimal places
Worked example
X% of Y: a shop offers 15% off a jacket priced at ₹2,400. Choose X% of Y and enter 15 and 2,400. The result is 360.00, so the discount is ₹360 and you pay ₹2,040. X is what % of Y: a student scores 412 marks out of 500. Enter 412 and 500 to get 82.40%.
% Increase/Decrease: a salary rises from ₹40,000 to ₹46,000. Change = (46,000 − 40,000) ÷ 40,000 × 100 = 15.00%, shown as an increase of 15.00%. If a price falls from 500 to 400, the calculator shows a decrease of 20.00%.
Frequently asked questions
How do I work out a discount with this calculator?
Use the X% of Y option. Enter the discount percentage as X and the original price as Y to get the discount amount, then subtract it from the price. For example, 15% of ₹2,400 is ₹360, so the sale price is ₹2,040.
What is the difference between a percentage and percentage points?
Percentage points describe the plain gap between two percentages, while percentage change compares them. A rate rising from 40% to 50% is 10 percentage points, but it is a 25% increase, which you can check with the Increase/Decrease option.
Why does a 20% fall followed by a 20% rise not return to the start?
Each percentage is taken on a different base. A fall from 500 to 400 is 20%, but a 20% rise on 400 only reaches 480. To get back to 500 you need a 25% rise.
Why do I see no result when I enter 0?
The calculator needs numbers other than zero in both boxes. Some answers are easy to work out yourself: 0% of any number is 0, and a fall from any amount to zero is a 100% decrease. A change that starts from zero cannot be shown as a percentage.
Can I use it to find my marks percentage?
Yes. Choose X is what % of Y, enter your marks obtained as X and the total marks as Y. For 412 out of 500 the answer is 82.40%. Results are rounded to two decimal places.
Limitations and accuracy
The calculator handles one calculation at a time and rounds to two decimal places. It does not work out reverse percentages, such as finding the original price from a discounted one, or chained discounts. For GST, use our GST Calculator. Percentage change is unreliable when the starting value is negative, because the formula divides by that value. Check results that matter, such as bills or exam marks, against official documents. This tool is for information only.