Percentage Calculator
Calculate X% of Y, find what percentage one number is of another, measure percentage increase or decrease, apply a percentage change, or work backwards to the original value.
Calculate a percentage
Find a percentage amount from a base value.
Example: 20% of 150 = 30.
What is a percentage?
A percentage is a way of expressing a value out of 100. The symbol % means “per hundred”, so 25% is the same as 25 out of 100, 0.25 as a decimal, or 1/4 as a fraction. Percentages are useful because they put different values on the same scale, making comparisons easier.
You will see percentages in exam marks, discounts, GST and tax, interest rates, salary hikes, business growth, tips, statistics, profit margins and many everyday calculations.
Percentage formulas
1. What is X% of Y?
Result = (X ÷ 100) × YExample: 20% of 150 = (20 ÷ 100) × 150 = 30.
2. X is what percent of Y?
Percentage = (X ÷ Y) × 100Example: 45 out of 180 = 25%.
3. Percentage change
% change = ((new − old) ÷ |old|) × 100Example: 80 to 100 is a 25% increase.
4. Increase or decrease by X%
New value = original × (1 ± X ÷ 100)Example: 120 increased by 15% = 138.
5. Reverse percentage
Original = final ÷ (1 ± X ÷ 100)Example: 92 after a 20% decrease came from 115.
Percent vs percentage points
Percentage points = new % − old %Moving from 4% to 6% is +2 percentage points, but a 50% relative increase.
Common percentage examples
| Question | Calculation | Answer |
|---|---|---|
| What is 18% of ₹50,000? | (18 ÷ 100) × 50,000 | ₹9,000 |
| 450 marks out of 600 is what percentage? | (450 ÷ 600) × 100 | 75% |
| Salary rises from ₹30,000 to ₹35,000 | ((35,000 − 30,000) ÷ 30,000) × 100 | 16.67% increase |
| ₹2,000 increased by 18% | 2,000 × 1.18 | ₹2,360 |
| ₹800 after a 20% discount came from what price? | 800 ÷ 0.80 | ₹1,000 |
How to use the Percentage Calculator
- Select the calculation type that matches your question.
- Enter the two values. The field labels change automatically for each mode.
- For increase/decrease or reverse percentage, choose whether the percentage was added or subtracted.
- Select Calculate or press Enter to see the answer, explanation and working.
- Use Copy result if you want to reuse the answer elsewhere.
Where percentage calculations are used
Marks and exam scores
Divide marks obtained by total marks and multiply by 100. For example, 450 out of 600 is 75%.
Discounts and sale prices
Find the discount amount with “X% of Y”, or use the increase/decrease mode to calculate the final sale price directly.
Salary, traffic and business growth
Percentage change compares a new value with an old one. It is commonly used for salary hikes, website traffic, revenue, costs and other performance metrics.
Tax, tips and markups
Use the increase-by-percentage mode when a percentage is added to a starting amount. For calculations with extra rules or multiple fields, a dedicated tax, discount or markup calculator may be more convenient.
Common percentage mistakes
- Using the wrong base: percentage change is measured against the original value, not the new value.
- Confusing percent and percentage points: a move from 20% to 25% is +5 percentage points but a 25% relative increase.
- Assuming equal increases and decreases cancel: +20% and then −20% produces 96 from an original 100.
- Dividing by zero: “X is what percent of Y?” and percentage change are undefined when the denominator is zero.
- Rounding too early: keep extra decimals during the calculation and round the final answer when needed.
Related calculators and guides
Frequently Asked Questions
How do I calculate a percentage of a number?
Multiply the number by the percentage and divide by 100. For example, 25% of 80 = (25 × 80) ÷ 100 = 20.
How do I find what percent one number is of another?
Divide the part by the whole and multiply by 100. For example, 30 out of 150 = (30 ÷ 150) × 100 = 20%.
How do I calculate percentage increase or decrease?
Subtract the original value from the new value, divide by the absolute original value and multiply by 100. A positive answer indicates an increase; a negative answer indicates a decrease.
How do I increase a number by 15%?
Multiply the number by 1.15. For example, 200 increased by 15% is 200 × 1.15 = 230.
How do I reverse a percentage?
If a final number is after a 20% decrease, divide the final value by 0.80. If it is after a 20% increase, divide by 1.20.
What is the difference between percent change and percentage points?
Percentage points compare two percentage values directly. Percent change measures the relative change from the starting percentage. A move from 4% to 6% is +2 percentage points and +50% relative change.
Are the values I enter stored?
The calculations on this page run in your browser. The entered values do not need to be sent to a server to produce the result.
Last updated: October 18, 2026. This calculator is for general mathematical use. Apply the rounding, tax or financial rules required for your specific situation.