Solve everyday percentage problems — find a percent, a share or a change.
Instant local calculation. Nothing is uploaded.
Understanding your result
A positive percent change means growth, a negative value means a decrease. Percentages are simply fractions out of one hundred, which makes them ideal for comparing different-sized quantities.
Formula and method
X% of Y = (X ÷ 100) × Y. X is what % of Y = (X ÷ Y) × 100. Percent change = ((New − Old) ÷ |Old|) × 100.
Worked example
25% of 200 = 50. 25 is 12.5% of 200. The change from 200 to 250 is a 25% increase.
How to use this tool
- Choose the type of percentage problem from the dropdown.
- Enter the two values the question needs.
- Press Calculate to see the answer and the working.
Common mistakes to avoid
- Confusing “percent of” with “percent change”.
- Dividing by the new value instead of the original when finding change.
- Forgetting that a 50% drop then a 50% rise does not return to the start.
About the Percentage Calculator
The Percentage Calculator handles the three percentage questions people ask most: finding a percentage of a number, finding what percentage one number is of another, and measuring the percentage change between two values.
Frequently asked questions
How is percentage change calculated?
Subtract the old value from the new value, divide by the old value, then multiply by 100.
Can it handle decimals and negatives?
Yes. The calculator accepts decimal and negative inputs and reports the result precisely.