Percentage Calculator
Three percentage calculators in one — runs locally, no upload.
Three ways to calculate percentages
This tool handles the three most common percentage problems in one place. Use X% of Y to find a portion of a number — for example, a discount or tip amount. Use X is what % of Y to express one number as a proportion of another. Use % change to measure how much a value has grown or shrunk between two points, which is common for tracking metrics, prices, or scores over time. All calculations run locally in your browser — nothing is sent anywhere.
Results update as you type, so there is no button to press. Switch between modes using the segment control at the top; each mode keeps its own inputs independently.
FAQ
What is X% of Y? Multiply Y by (X / 100). For example, 15% of 200 is 200 × 0.15 = 30.
How do I find what percent X is of Y? Divide X by Y and multiply by 100. For example, 30 out of 200 is (30 / 200) × 100 = 15%.
How is percent change calculated? Subtract the original value from the new value, divide by the absolute original value, and multiply by 100. A positive result means an increase; a negative result means a decrease.
What happens if the original value is zero? Percent change is undefined when the starting value is zero, so the calculator returns 0 to keep the output clean.