Percentage Calculator
Find what X% of a number is, instantly.
Results update as you type.
How it works
A percentage expresses a quantity as a portion of one hundred, which is why the word literally means 'per hundred.' When you find a percentage of a number, you are scaling that number down or up to the share the percentage represents. The percentage calculator does this in two clean steps: it converts the stated percentage into its decimal equivalent by dividing by 100, then multiplies that decimal by the value you are measuring against. Working 20% of 150, for instance, turns 20 into 0.2 and returns 0.2 times 150, which is 30. Percentages matter because they let people compare quantities on a common scale regardless of the underlying totals, so a 20% share means the same relative amount whether the base is 150 or 15,000. This shared scale is what makes the decimal-and-multiply method the standard approach; it mirrors the definition of a percentage exactly and avoids the rounding drift that mental shortcuts introduce. The tool removes that friction entirely and keeps the result exact. Shoppers use a percentage calculator for discounts and sales tax, students apply it to test scores and lab results, and finance and retail professionals lean on it for margins, tips, commissions and interest. Anywhere a part-of-a-whole relationship appears, this percentage calculator turns it into a precise figure.
result = (percentage ÷ 100) × value
Dividing the percentage by 100 restores its true meaning as a fraction of one hundred, converting 20% into the decimal 0.2. Multiplying that decimal by the value then takes exactly that fraction of the whole, so 0.2 times 150 yields 30. The two operations mirror the definition of a percent directly: express the part per hundred, then apply it to the actual base amount.
Source:Standard arithmetic
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Worked example
How to use this calculator
- 1
Enter your values
Enter percentage and of value.
- 2
Adjust the options
Fine-tune any options to match your situation.
- 3
Read your result
Result updates instantly as you type — no button to press.
Frequently asked questions
What is a percentage?
A percentage is a way of writing a number as a fraction of one hundred, marked by the percent sign. Saying 20% is identical to saying 20 out of 100, or the decimal 0.2. Because every percentage shares the same base of one hundred, percentages let you compare portions drawn from totals of any size on one consistent scale, which is what makes them so widely used.
How do I calculate a percentage of a number?
Turn the percentage into a decimal by dividing it by 100, then multiply that decimal by the number you are measuring. For 20% of 150, divide 20 by 100 to get 0.2, then multiply by 150 to reach 30. The order never changes the answer, and doing both steps keeps the figure exact rather than rounded from a mental estimate.
How do I convert a percentage to a decimal?
Divide the percentage by 100, which shifts the decimal point two places to the left. That converts 20% into 0.2 and 5% into 0.05. Reversing the process by multiplying a decimal by 100 turns it back into a percentage, so 0.2 becomes 20%. This conversion is the first step in almost every percentage calculation and keeps the arithmetic aligned with the definition of a percent.
Can I use this to work out a discount?
Yes. Find the percentage of the original price first, then subtract it. On a 150 item marked 20% off, take 20% of 150, which is 30, and subtract to reach a sale price of 120. To go the other way and add sales tax or a tip, calculate the percentage the same way and add it to the base amount instead of subtracting.
Why divide by 100 instead of using the percentage number directly?
The percent sign already means divided by one hundred, so 20% is not the number 20; it is 20/100, or 0.2. Multiplying a value by the raw 20 would scale it twenty times over instead of taking a fifth of it. Dividing by 100 first restores the intended proportion, which is why 20% of 150 correctly gives 30 rather than 3,000.