Core formulas
X% of Y is (X ÷ 100) × Y. X as a percent of Y is (X ÷ Y) × 100. Percentage change is ((new − original) ÷ |original|) × 100.
Calculators · Local processing
Percentage Calculator
Solve common percentage questions with clear, instant results and no tracking.
Calculate locally
Solve a percentage
Result20
The practical guide
Choose the percentage question that matches your problem.
Use the dedicated modes to avoid rearranging formulas mentally.
Simple example
Twenty percent of 50 is 10. Adding 20% to 50 gives 60, while subtracting 20% gives 40.
Privacy by architecture
Your files and tool inputs stay in your browser.
The selected files, inputs, settings, and outputs are processed in this page and are not uploaded to any server.
Questions, answered
Frequently asked questions
Can the calculator use decimals?
Yes. Both inputs accept decimal and negative numbers.
Why can the reference value not be zero?
Division by zero has no finite percentage result.
Are values sent anywhere?
No. The arithmetic happens in this browser.