Percentage Calculator
Choose a common percentage question, enter the values, and get a clear result with the formula shown.
A QUICK WALKTHROUGH
How to use this tool
- Choose the percentage calculation you need.
- Enter the requested values and select Calculate.
- Review the result and formula, then copy it if needed.
Common percentage questions
Use percentage of to find a part of a number, increase or decrease to apply a percentage change, and percent change to compare an original and a new value. Reverse percentage finds the original value before a known increase or decrease.
Clear inputs and formulas
Values may be positive, zero, or negative where the selected formula permits them. The calculator rejects missing, non-finite, and undefined operations instead of silently returning a misleading number.
Private browser calculation
All parsing and arithmetic happen locally in your browser. Your values are not uploaded or stored by this page.
GOOD TO KNOW
Common questions
How do I calculate a percentage of a number?
Choose Percentage of, enter the percentage and the number, then calculate. The result is percentage ÷ 100 × number.
How is percent change calculated?
Percent change is (new value − original value) ÷ original value × 100. The original value cannot be zero.
What is a reverse percentage?
It finds the starting value when you know the final value and the percentage increase or decrease that was applied.
Can I use negative values?
Yes for percentage amounts and comparisons. A reverse increase or decrease must leave a nonzero multiplier.