How to use the Percentage Calculator
- 1Pick the calculator that matches your question: What is X% of Y?, X is what percent of Y?, or Percentage change from X to Y.
- 2Type the two numbers into that calculator's fields.
- 3Read the answer, which updates as you type.
- 4For percentage change, check whether the result is shown as an increase or a decrease.
How to find X% of a number
To find a percentage of a number, divide the percentage by 100 and multiply by the number: result = (X ÷ 100) × Y. For example, 15% of 80 is 0.15 × 80 = 12. This is the calculation behind discounts, tips, tax amounts and commission.
A handy shortcut is that X% of Y always equals Y% of X. So 8% of 50 is the same as 50% of 8, which is easy to do in your head: 4. For more worked examples, see our guide on how to calculate percentages.
How to find what percent X is of Y
To express one number as a percentage of another, divide the part by the whole and multiply by 100: percent = (X ÷ Y) × 100. For example, 30 out of 120 is (30 ÷ 120) × 100 = 25%. This is useful for test scores, budget shares and completion rates. A fraction converts the same way: 3/8 is (3 ÷ 8) × 100 = 37.5%, and the fraction calculator helps when you need to simplify or combine fractions first.
The order matters. 30 is 25% of 120, but 120 is 400% of 30. Make sure the whole, the number you are comparing against, goes in the Y field.
How to calculate percentage increase or decrease
Percentage change compares a new value with an original value: change = ((new − original) ÷ original) × 100. A positive result is an increase and a negative result is a decrease. If a price rises from 50 to 65, the change is ((65 − 50) ÷ 50) × 100 = 30% increase. If it falls from 80 to 60, the change is ((60 − 80) ÷ 80) × 100 = −25%, a 25% decrease.
Increases and decreases are not symmetric. A 25% drop from 80 to 60 needs a 33.3% rise to get back to 80, because the second change is measured from the smaller number. Percentage change is undefined when the original value is zero. Repeated percentage gains build on each other in the same way, which the compound interest calculator shows over many years.
Percent vs percentage points
When comparing two percentages, the difference can be described in two ways. If an interest rate goes from 4% to 5%, it has risen by 1 percentage point, but it has increased by 25% in relative terms, since 1 is 25% of 4. News reports and financial documents usually use percentage points for the absolute gap to avoid confusion.
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Frequently asked questions
How do I calculate a discount?
Use the What is X% of Y? calculator with the discount rate as X and the original price as Y to get the amount saved. Subtract that from the original price to get the sale price. For a 20% discount, you can also multiply the price by 0.8 directly. The discount calculator does both steps at once.
How do I add a percentage to a number?
Multiply the number by 1 plus the percentage as a decimal. For example, adding 10% to 250 gives 250 × 1.10 = 275. This is how tax or a markup is usually added. To add or remove sales tax or VAT directly, use the sales tax calculator.
What is the difference between percentage change and percentage difference?
Percentage change measures movement from an original value to a new one, so direction matters. Percentage difference compares two values without treating either as the starting point, usually by dividing the gap by their average. This page calculates percentage change.
Can a percentage be more than 100%?
Yes. A value can be more than 100% of another, such as 150 being 150% of 100, and an increase can exceed 100%, such as doubling, which is a 100% increase. A decrease, however, cannot be more than 100% for positive quantities.
Are my numbers saved?
No. Calculations run in your browser and nothing is sent or stored.