Percent of a value
What is X% of Y?
Answer12
Math calculator
Percentage Calculator
Solve percent of a number, one value as a percent of another, reverse percentage, percentage change and percent conversion.
x / 100 × y
Percent ratio
X is what % of Y?
Answer20%
Reverse percent
X is Y% of what?
Answer60
Percent change
Percentage change from start to final
Answer25%
Percent converter
Percent to decimal, fraction and PPM
Decimal0.125
Fraction1/8
PPM125000 ppm
Percentage calculation examples
Percent of a value
20% × 60 = 12
Percent ratio
12 / 60 × 100 = 20%
Whole value
12 / 0.20 = 60
Percent change
(50 - 40) / 40 × 100 = 25%
Percentage formulas
| Question | Formula | Example |
|---|---|---|
| What is X% of Y? | X / 100 × Y | 20 / 100 × 60 = 12 |
| X is what % of Y? | X / Y × 100 | 12 / 60 × 100 = 20% |
| X is Y% of what? | X / (Y / 100) | 12 / 0.20 = 60 |
| Percent change | (final - start) / start × 100 | (50 - 40) / 40 × 100 = 25% |
Percentage calculator FAQ
How do I calculate 20% of a number?
Convert 20% to 0.20 and multiply by the number.
What is percent change?
Subtract the start from the final value, divide by the start, then multiply by 100.
Can I use negative numbers?
Yes. A zero starting value makes percentage change undefined.
How is a percent converted to a fraction?
Divide by 100 and simplify the resulting fraction.
Handy Tool Lab
How this tool is maintained
Handy Tool Lab builds and tests each tool around repeatable examples. Formula-based tools use published references when a suitable source exists; browser utilities are checked with representative inputs and output cases.