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What this percentage calculator can solve
Use the three calculation modes for common school, shopping, finance and business questions. The first mode finds a percentage of a number. The second shows what percentage one value is of another. The third measures an increase or decrease from an original value.
Percentage formulas
X% of Y = (X ÷ 100) × Y
X is what % of Y = (X ÷ Y) × 100
Percentage change = ((new − original) ÷ |original|) × 100
Worked percentage examples
Common uses
- Calculate exam or marks percentages.
- Find a sale discount or price increase.
- Measure growth in revenue, users or expenses.
- Compare one value with a total.
Important calculation notes
For “what percent” questions, the second value is the base and cannot be zero. For percentage change, the original value is the base. A result above zero is an increase and a result below zero is a decrease.
Frequently asked questions
How do I calculate a percentage of a number?
Multiply the number by the percentage and divide by 100. For example, 20% of 500 is 100.
How do I find what percent one number is of another?
Divide the first value by the comparison value and multiply by 100.
How is percentage increase calculated?
Subtract the original value from the new value, divide by the absolute original value and multiply by 100.
Can I use decimal values?
Yes. Whole numbers and decimals are supported.
Are my values saved?
No. The calculation stays in your browser.
Calculator logic and page wording reviewed on July 19, 2026.