Percentage Calculator
Calculate percentages, percentage change, and more instantly.
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Percentage Calculator
Percentage Calculations Explained
Percentages are one of the most practical math concepts in everyday life — used in shopping discounts, tax calculations, interest rates, test scores, and statistical analysis. A percentage expresses a number as a fraction of 100, making it easy to compare different quantities on a common scale.
Common Percentage Formulas
| Calculation | Formula | Example |
|---|---|---|
| X% of Y | (X/100) × Y | 15% of 200 = 30 |
| X is what % of Y? | (X/Y) × 100 | 30/200 × 100 = 15% |
| % Change | [(New–Old)/Old] × 100 | (110–100)/100 × 100 = 10% |
| Original before % increase | Final ÷ (1 + %/100) | 110 ÷ 1.10 = 100 |
Frequently Asked Questions
How do I calculate what percent one number is of another?
Divide the part by the whole and multiply by 100. Example: What percent is 30 of 150? → (30 ÷ 150) × 100 = 20%.
How do I calculate a percentage increase or decrease?
Percentage Change = [(New Value – Old Value) ÷ Old Value] × 100. A positive result is an increase; a negative result is a decrease. Example: From 80 to 100 → (20 ÷ 80) × 100 = 25% increase.
How do I find the original value before a percentage was applied?
Divide the final value by (1 + rate/100) for an increase, or (1 – rate/100) for a decrease. Example: If a price increased 20% to $120, original = 120 ÷ 1.20 = $100.
What is a percentage point vs. a percent change?
A percentage point is an absolute difference between two percentages. Example: Going from 10% to 15% is a 5 percentage point increase, but a 50% relative increase. The distinction matters greatly in finance, economics, and statistics.
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