Percentage Calculator
Calculate percent of a number, what percent one value is of another, and percentage increase or decrease.
X% of Y
Enter values below to calculate.
Result
Calculated answer and breakdown.
Result
30
15% of 200 = 30
Quick reference for 200
Methodology and limitations
Last reviewed:
Methodology
Computes percent-of-value, what-percent comparisons, and percent increase/decrease using standard percentage formulas.
Limitations
Results are mathematical estimates; verify for financial or contractual use.
How to Calculate Percentages
Calculate percent of a number, what percent one value is of another, and percentage increase or decrease.
Method used
The calculator applies the selected percentage formula for percent-of, part-over-whole percentage, or percent change.
Percent change = (new value - original value) / original value x 100
Practical example
For 15% of 200, convert 15% to 0.15 and multiply by 200 to get 30.
- Mode: X% of Y
- Percentage: 15
- Number: 200
The result shows the calculated value and a plain-language explanation of the formula used.
Assumptions
- Percent values are entered as percentages, not decimals.
- Percent change needs a nonzero original value.
- What-percent mode needs a nonzero whole value.
What this includes
- Percent of a number, what percent X is of Y, percent increase, percent decrease, and quick-reference values.
What this excludes
- Sales tax rules, discounts with item restrictions, statistical confidence intervals, and financial return assumptions.
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Frequently Asked Questions
How do I calculate X percent of Y?
Convert the percent to a decimal and multiply by the number. For example, 15% of 200 is 0.15 x 200 = 30.
How do I find what percent one number is of another?
Divide the part by the whole, then multiply by 100. For example, 30 out of 200 is 15%.
How is percent change calculated?
Subtract the original value from the new value, divide by the original value, then multiply by 100.