How to use the Percentage Calculator
- Choose what you want to work out from the drop-down list. The labels of the two boxes change to match.
- Type your two numbers. Commas are fine, so you can write 1,50,000.
- Press Calculate to see the answer and the working.
- Use Copy result to paste the answer elsewhere, or Reset to start again.
Percentage formulas
Worked examples
15% of 800: (15 ÷ 100) × 800 = 120.
45 is what % of 60: (45 ÷ 60) × 100 = 75%.
Salary rises from 50,000 to 56,000: (56,000 − 50,000) ÷ 50,000 × 100 = 12% increase.
A ₹2,000 item plus 18% tax: 2,000 × 1.18 = ₹2,360.
Where percentages come up in daily life
- Discounts and sales: a 25% discount means you pay 75% of the price, so the sale price is price × 0.75.
- Tax on bills: GST and other taxes are a percentage added to a base price.
- Marks and grades: percentage = marks obtained ÷ total marks × 100.
- Growth and returns: salary hikes, price rises and investment returns are all percentage changes.
- Interest rates: a loan or deposit rate is a percentage of the amount per year.
Common mistakes to avoid
- Using the wrong base. A percentage change is always measured against the starting (old) value, not the new one.
- Adding successive percentages. A 10% rise followed by another 10% rise is 21% overall, not 20%, because the second 10% is taken on the larger amount (100 → 110 → 121).
- Mixing up percent and percentage points. Going from 40% to 50% is a rise of 10 percentage points but a 25% increase.
- Forgetting to convert. 8% is 0.08 as a decimal. Multiplying by 8 instead of 0.08 is the most common slip.
Frequently asked questions
How do I calculate a percentage of a number?
Divide the percentage by 100 and multiply by the number. For example, 20% of 250 is 0.20 × 250 = 50.
What is the difference between percent and percentage points?
If a rate moves from 10% to 12%, it has risen by 2 percentage points, but by 20 percent (2 ÷ 10). Percentage points describe the simple gap; percent describes the relative change.
How do I find the original price before a discount?
Divide the final price by (1 − discount ÷ 100). If a shirt costs ₹800 after a 20% discount, the original price was 800 ÷ 0.80 = ₹1,000.
Why is a 50% increase followed by a 50% decrease not back to the start?
The second percentage is taken on a bigger number. 100 + 50% = 150, and 150 − 50% = 75, not 100. To undo a 50% rise you need a decrease of about 33.3%.
Why does the calculator refuse an old value of zero?
A percentage change is measured relative to the starting value. When that value is zero the ratio is undefined, so there is no meaningful percentage to report.
How do I calculate a discount?
Multiply the price by the discount percentage and divide by 100 to get the amount off, then subtract it. A ₹1,200 item at 30% off saves 1,200 × 30 ÷ 100 = ₹360, so you pay ₹840.
How do I find my marks percentage?
Divide the marks you scored by the total marks and multiply by 100. For example, 432 out of 600 is 432 ÷ 600 × 100 = 72%.