Percentage Calculator
Calculate percentages quickly and easily. Discounts, increases, VAT and more.
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How to calculate percentages
Percentages are used everywhere: discounts, taxes, interest rates, statistics and everyday math. Knowing how to calculate them is a very useful skill that eases financial decisions.
The percentage formula
Percentage × Total ÷ 100
To find X% of Y, multiply X by Y and divide by 100. For example, 20% of 150 = (20 × 150) ÷ 100 = 30.
Real examples
- Discount: an item of €50 with a 15% discount saves you €7.50.
- Taxes: a €100 product with 21% VAT has €21 of tax.
- Increase: a salary rise from €2,000 to €2,200 is a 10% increase.
- Grades: 18 out of 20 equals 90%.
Common mistakes when calculating percentages
- Confusing the percentage with the final value: 20% of 150 is not 20, but 30. You must multiply the percentage by the total and divide by 100.
- Forgetting that adding 10% and then removing 10% does not return to the original value: a 10% increase followed by a 10% discount always ends below the initial price.
- Applying the percentage to the wrong base when calculating increases or decreases.
When to use each mode
Use "X% of Y" when you want to know the part of a total, "X is what % of Y" to compare two values, and "Increase" or "Decrease" when you have an initial and a final value and want to know how much it changed in percentage terms.
Frequently Asked Questions
How do I calculate a percentage?
Enter the percentage and the base amount. The tool calculates the result automatically.
How do I calculate 20% of 150?
Select "What is X% of Y", enter 20 in the first field and 150 in the second. The result is 30.
How do I calculate a percentage discount?
Use the "Decrease" mode. Enter the discount percentage and the original price.