How to Use the Percentage Calculator
- Choose the calculation type. This tool has four sections: finding a percentage of a number, finding what percent one number is of another, calculating percentage change, and calculating percentage increase or decrease.
- Enter your numbers into the input fields. All calculators accept decimal values for precision.
- Click "Calculate" to see the result instantly. For increase/decrease, click the corresponding button to choose the direction.
Percentage Formulas Explained
Finding X% of Y: Multiply Y by X and divide by 100. Example: 25% of 200 = (200 × 25) / 100 = 50.
Finding what percent X is of Y: Divide X by Y and multiply by 100. Example: 50 is what percent of 200? (50 / 200) × 100 = 25%.
Percentage change: Subtract the old value from the new value, divide by the absolute old value, and multiply by 100. Example: from 100 to 150 = ((150 - 100) / |100|) × 100 = 50% increase.
Increase/Decrease: Multiply the original value by the percentage and divide by 100, then add (increase) or subtract (decrease) from the original. Example: 200 increased by 15% = 200 + (200 × 0.15) = 230.
Common Use Cases
- Shopping discounts - Calculate how much you save during sales. A 30% discount on a Rs. 2,000 item saves Rs. 600.
- Tax and tip calculations - Quickly compute GST, service tax, or restaurant tips as a percentage of the bill.
- Grade and score analysis - Convert raw scores to percentages for academic grading or exam results.
- Business metrics - Calculate profit margins, growth rates, year-over-year changes, and commission percentages.
Tips
- To calculate a percentage of a percentage, convert both to decimals and multiply. For example, 50% of 40% = 0.50 × 0.40 = 0.20 = 20%.
- A 50% increase followed by a 50% decrease does not return you to the original value. 100 + 50% = 150, then 150 - 50% = 75.
- Use the "X is what % of Y" calculator to quickly convert fractions to percentages.
Common Percentage Calculations
Quick reference for everyday percentage calculations:
| Scenario |
Percentage |
On Rs. 1,000 |
On Rs. 5,000 |
On Rs. 10,000 |
| Restaurant Tip (Standard) | 10% | Rs. 100 | Rs. 500 | Rs. 1,000 |
| Restaurant Tip (Generous) | 15% | Rs. 150 | Rs. 750 | Rs. 1,500 |
| Restaurant Tip (Excellent) | 20% | Rs. 200 | Rs. 1,000 | Rs. 2,000 |
| GST (Standard) | 18% | Rs. 180 | Rs. 900 | Rs. 1,800 |
| GST (Food) | 5% | Rs. 50 | Rs. 250 | Rs. 500 |
| Sale Discount (Common) | 20% | Rs. 200 | Rs. 1,000 | Rs. 2,000 |
| Sale Discount (Big) | 30% | Rs. 300 | Rs. 1,500 | Rs. 3,000 |
| Sale Discount (Mega) | 50% | Rs. 500 | Rs. 2,500 | Rs. 5,000 |
| Service Charge | 10% | Rs. 100 | Rs. 500 | Rs. 1,000 |
Percentage to Fraction Conversion
| Percentage |
Decimal |
Fraction |
Simplified |
| 5% | 0.05 | 5/100 | 1/20 |
| 10% | 0.10 | 10/100 | 1/10 |
| 12.5% | 0.125 | 12.5/100 | 1/8 |
| 20% | 0.20 | 20/100 | 1/5 |
| 25% | 0.25 | 25/100 | 1/4 |
| 33.33% | 0.333 | 33.33/100 | 1/3 |
| 50% | 0.50 | 50/100 | 1/2 |
| 66.67% | 0.667 | 66.67/100 | 2/3 |
| 75% | 0.75 | 75/100 | 3/4 |
| 100% | 1.00 | 100/100 | 1/1 |
Percentage Change Examples
Worked examples showing how percentage change is calculated:
| From |
To |
Change |
Formula |
Result |
| 100 | 150 | +50 | (150-100) / 100 × 100 | +50% increase |
| 200 | 160 | -40 | (160-200) / 200 × 100 | -20% decrease |
| 80 | 100 | +20 | (100-80) / 80 × 100 | +25% increase |
| 500 | 550 | +50 | (550-500) / 500 × 100 | +10% increase |
| 1000 | 850 | -150 | (850-1000) / 1000 × 100 | -15% decrease |
| 40 | 50 | +10 | (50-40) / 40 × 100 | +25% increase |
| 250 | 300 | +50 | (300-250) / 250 × 100 | +20% increase |