Percentage Calculator
Calculate percentages quickly and accurately
Use this percentage calculator to compute percentage increase or decrease, determine what percent one value is of another, or calculate a percentage of a given number. It is designed for fast, accurate, and easy everyday calculations.
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What is a percentage calculator?
A percentage calculator helps you understand how numbers relate to each other in terms of percentages. Percentages are widely used in finance, education, statistics, shopping discounts, and everyday decision-making.
How we calculate percentages
This calculator uses standard percentage formulas based on a part and a whole(or an original and a new value). For “what percent is X of Y”, we divide the part by the whole and multiply by 100. For “percentage of a number”, we convert the percent to a decimal and multiply. For “increase/decrease”, we compute the change relative to the original value.
Note: If the original (or whole) is 0, a percentage comparison is undefined because division by zero isn’t possible. In that case, use the calculator’s other modes or change inputs.
How percentage increase and decrease works
Percentage change shows how much a value has increased or decreased relative to its original value.
Percentage Change = (New − Original) ÷ Original × 100
Finding what percent one number is of another
This calculation determines how large one value is in relation to a total value, expressed as a percentage.
Percentage = Part ÷ Whole × 100
Calculating a percentage of a number
This option allows you to find a specific percentage of a given number, such as calculating discounts, taxes, or tips.
Result = Percentage ÷ 100 × Number
Examples
Percentage increase
A price goes from 80 to 100:(100 − 80) ÷ 80 × 100 = 25%
Percentage decrease
A value drops from 250 to 200:(200 − 250) ÷ 250 × 100 = −20%
What percent is X of Y?
20 is what percent of 250:20 ÷ 250 × 100 = 8%
Percentage of a number
15% of 120:15 ÷ 100 × 120 = 18
Tip: For comparisons, keep units consistent (e.g., same currency, same measurement system).
Common uses for percentage calculations
- Shopping discounts and sales
- Financial analysis and budgeting
- Exam scores and grading
- Business growth comparisons
- Statistical and data analysis
Frequently Asked Questions
What’s the difference between percent and percentage points?
Percent is relative change (e.g., +10%). Percentage points describe absolute differences between two percentages (e.g., from 40% to 50% is +10 percentage points).
Why can’t I calculate a percent change when the original value is 0?
Percent change divides by the original value. If the original is 0, the calculation is undefined (division by zero).
Can percentage change be negative?
Yes. A decrease results in a negative percentage change (for example, −20% means the value dropped by 20% relative to the original).
What if the “part” is bigger than the “whole”?
Then the result is above 100%. For example, 150 is 150% of 100.
How does rounding work?
Small differences are normal depending on how many decimals you display. For consistent comparisons, keep the same rounding across scenarios.
Are these calculations suitable for finance or legal documents?
They’re mathematically correct, but for official documents you should verify assumptions, rounding rules, and any domain-specific definitions.
Disclaimer
This Percentage Calculator is provided for general informational purposes only. Results should not be considered financial, legal, or professional advice. Always verify important calculations independently.