Six independent calculators for percentages: find what percent of a number, compare values, measure change, and reverse-calculate the base. Formulas shown step-by-step with your actual numbers.
| Question | Formula | Worked Example |
|---|---|---|
| What is P% of X? | Result = X × (P / 100) | What is 25% of 200? → 200 × (25/100) = 50 |
| X is what % of Y? | Result = (X / Y) × 100 | 50 is what % of 200? → (50/200) × 100 = 25% |
| Percentage change from X to Y | Result = ((Y − X) / |X|) × 100 | Change from 150 to 200? → ((200−150)/150) × 100 = 33.33% increase |
| Increase X by P% | Result = X × (1 + P/100) | Increase 100 by 20%? → 100 × 1.2 = 120 |
| Decrease X by P% | Result = X × (1 − P/100) | Decrease 100 by 15%? → 100 × 0.85 = 85 |
| X is P% of what? | Result = X / (P / 100) | 50 is 25% of what? → 50 / (25/100) = 200 |
These terms sound similar but measure different things:
(new − old) / |old| × 100. Example: a rise from $50 to $60 is a 20% increase.| Fraction | Decimal | Percent |
|---|---|---|
| 1/2 | 0.5 | 50% |
| 1/3 | 0.333… | 33.33% |
| 1/4 | 0.25 | 25% |
| 1/5 | 0.2 | 20% |
| 1/8 | 0.125 | 12.5% |
| 2/3 | 0.667… | 66.67% |
| 3/4 | 0.75 | 75% |
Yes. The calculator uses the absolute value of the starting number in the denominator, which means a change from −$10 to +$10 is a 200% increase. This is the standard convention in finance and statistics, as it prevents division by zero and maintains a logical interpretation of growth.
Percentage change is a relative measure: how much something grew compared to its starting value. Percentage points measure an absolute difference between two percentages. If interest rates rose from 2% to 5%, that's a 3 percentage point increase, not a 150% increase. The "percentage points" section above has more detail.
Most percentages don't divide evenly, so they produce repeating decimals. The rounded result (up to 4 significant digits) is what you'd use in practice, but the "exact" line shows the full calculation in case you need it for academic work or to verify your own calculations.
Yes. The calculator strips commas, % signs, and common currency symbols before parsing, so pasting "1,000" or "$500" or "25%" works fine.
The calculator alerts you to the problem instead of showing "Infinity" or "NaN". Division by zero is undefined in mathematics, and the message explains why the calculation cannot proceed.
Use the first calculator ("What is P% of X?") to find your weighted points (e.g., "What is 85% of 100 possible points?"), or the second ("X is what % of Y?") to find your percentage on a test (e.g., "I got 42 points out of 50—what percent is that?"). For more advanced GPA calculations, see our GPA calculator.