Percentage Calculator
Answer the four most common percentage questions instantly: X% of a number, what percent one number is of another, the percentage change between two values, and the original value before a percentage change.
What is X% of Y?
Enter both values — the result appears as you type.
Formula: Result = (percentage ÷ 100) × value
Copy the result as a short sentence.
Calculations run in your browser. Nothing you enter is sent to our servers.
How to use Percentage Calculator
- 1
Choose a calculation
Pick % of a number, X is what %, % change or Original value. “Try an example” fills in sample numbers.
- 2
Enter the numbers
Type whole numbers or decimals — negative numbers and commas such as 1,000 or 1,00,000 work too. The result updates as you type.
- 3
Read and copy the result
See the answer with the formula worked out using your numbers. Use Copy result to copy it as a sentence, or Reset to start again.
Frequently asked questions
How do I calculate X% of a number?
Divide the percentage by 100 and multiply by the number. For example, 20% of 500 is (20 ÷ 100) × 500 = 100.
How do I find what percent one number is of another?
Divide the part by the whole and multiply by 100. For example, 25 is (25 ÷ 200) × 100 = 12.5% of 200. The whole can’t be 0.
How is percentage change calculated?
Subtract the original value from the new value, divide by the original value and multiply by 100. From 800 to 1,000 is ((1,000 − 800) ÷ 800) × 100 = a 25% increase; from 1,000 to 800 is a 20% decrease. For negative originals the calculator divides by the size of the original, so a rise is always shown as an increase.
Why is there no percentage change from 0?
Any change from 0 would be an infinitely large percentage, so it isn’t defined. The calculator shows the change in value instead — or 0% if both values are 0.
How do I find the original value before an increase or decrease?
Divide the final value by (1 + percentage ÷ 100) after an increase, or by (1 − percentage ÷ 100) after a decrease. 1,000 after a 25% increase was 800; 800 after a 20% decrease was 1,000. A decrease of 100% or more can’t be reversed.
Are the results rounded?
Results are shown with up to 6 decimal places and marked with ≈ when rounded. Calculations use full precision, so nothing is rounded along the way.