% Percentage Calculator
Three calculators in one — pick the question you're trying to answer.
How These Calculations Work
What is X% of Y? Multiply Y by (X ÷ 100). Example: 15% of 200 = 200 × 0.15 = 30.
X is what % of Y? Divide X by Y, then multiply by 100. Example: 30 is what % of 200 → (30 ÷ 200) × 100 = 15%.
Percentage change from X to Y? Subtract X from Y, divide by X, then multiply by 100. A positive result is an increase, a negative result is a decrease. Example: from 80 to 100 → ((100-80) ÷ 80) × 100 = 25% increase.
Frequently Asked Questions
What is the difference between percentage and percentage points?
A percentage point is the arithmetic difference between two percentages (e.g. going from 20% to 25% is a
5 percentage point increase), while a percentage change describes that same move relative to the starting
value (a 25% increase, since 5 is 25% of 20).
Guide: understanding your result
- X% of Y = Y × X ÷ 100. "A is what percent of B?" = A ÷ B × 100. Percentage change = (New − Old) ÷ Old × 100.
- A rise of X% followed by a fall of X% does not return to the start: +20% then −20% leaves you 4% lower.
- Percentage points measure the difference between two percentages: a rate moving from 4% to 5% rose 1 point, or 25%.
Formulas with examples
| Question | Formula | Example |
|---|---|---|
| What is 15% of 240? | 240 × 15 ÷ 100 | 36 |
| 45 is what % of 180? | 45 ÷ 180 × 100 | 25% |
| Change from 80 to 100? | (100 − 80) ÷ 80 × 100 | +25% |
| Change from 100 to 80? | (80 − 100) ÷ 100 × 100 | −20% |
| Original before a 25% increase to 150? | 150 ÷ 1.25 | 120 |
Common mistakes to avoid
- Dividing by the new value instead of the old one when calculating change.
- Adding successive percentage changes instead of multiplying them.
Frequently asked questions
How do I reverse a percentage increase?
Divide by (1 + the increase). A price of $138 after a 15% increase was $138 ÷ 1.15 = $120.
Examples are calculated live from the same data the calculator uses and are for education only — they are not financial, tax or investment advice.
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