Business
Percentage Calculator
Solve common percentage questions and calculate percentage increases or decreases with clear results.
How to use this tool
- Choose the calculation that matches your question: percent of a number, proportion as a percent, or percentage change.
- Enter both numbers in the labeled fields. Decimals are accepted.
- Select Calculate and read the result card, or correct any validation message shown.
- Use Clear before starting a separate calculation to avoid mixing inputs.
Practical examples
Find 15% of a 240-unit project budget: the result is 36 units.
Calculate that 45 completed tasks out of 60 equals 75%.
Measure a change from 80 to 92 as a 15% increase.
Measure a change from 200 to 170 as a 15% decrease.
Common mistakes to avoid
- Swapping the percentage and base number in an X% of Y calculation.
- Using the new value as the denominator when measuring percentage change.
- Attempting percentage change from zero, which has no finite percentage result.
- Rounding inputs too early instead of rounding only the final result.
Useful internal links
Frequently Asked Questions
How do I calculate X percent of Y?
Choose X% of Y, enter the percentage first and the base number second. The calculation multiplies Y by X divided by 100.
How is percentage change calculated?
The difference between the new and original values is divided by the absolute original value, then multiplied by 100.
Can I enter decimal or negative values?
Yes. Decimal and negative values are accepted, although you should interpret negative baselines carefully for your specific use case.
Why can the original value not be zero for percentage change?
Percentage change divides by the original value, so a zero starting point does not produce a finite percentage.