Percentage Calculator
Calculate percentages easily — find what X% of Y is, what percentage X is of Y, percentage change, and more.
What is X% of Y?
X is what % of Y?
Percentage Change (Increase / Decrease)
Find Original Value (before % change)
About this calculator
Percentages show up in discounts, interest, marks, tax, tips and growth, and there are four different questions people ask about them. This calculator answers all four on one page: what is X% of Y, X is what percent of Y, how much did a value change in percent, and what was the original value before a percentage change.
Each block updates as you type, so you can explore "what if" numbers without pressing anything. Use it for sale prices, exam scores, salary hikes or checking a bill.
How to use it
- Pick the block that matches your question.
- Type the two numbers it asks for.
- Read the answer beside the equals sign. Change a number to try another case.
The four formulas
X% of Y = Y × X ÷ 100. X is what % of Y = X ÷ Y × 100. Change % = (New − Old) ÷ Old × 100. Original = Final ÷ (1 + Change% ÷ 100).
Worked example
Worked examples
| 20% of 150 | 30 |
| 30 is what % of 200 | 15% |
| 80 to 100 | +25% increase |
| Final 120 after a 20% rise | Original was 100 |
Notice the asymmetry: a 25% rise from 80 to 100 is undone only by a 20% fall from 100 to 80, not 25%.
Tips and common mistakes
- Percent means per hundred. 7% is 7 out of 100, or 0.07.
- To add a percentage, multiply by 1 plus the rate: +18% GST is × 1.18.
- To remove a percentage that was added, divide, don't subtract. ₹1,180 incl. 18% GST is ₹1,000 before tax.
- Percentage points and percent differ: going from 10% to 12% is +2 points, or +20%.
- Successive percentage changes multiply; they do not add.
Frequently asked questions
How do I calculate a percentage of a number?
Multiply the number by the percentage and divide by 100.
How do I find what percent one number is of another?
Divide the first by the second and multiply by 100.
How do I calculate percentage increase?
Subtract the old value from the new, divide by the old, and multiply by 100.
How do I find the original price after a discount?
Divide the sale price by one minus the discount rate, for example ₹800 after 20% off was ₹1,000.
What is the difference between percent and percentage points?
Percent compares relative size; points are the plain difference between two percentages.
Can a percentage be more than 100?
Yes. 150% means one and a half times the base.