How the Percentage Calculator Works

Our calculator solves three types of percentage problems instantly. Here's how each one works:

What is X% of Y?

Enter a percentage and a number. The calculator multiplies the number by the percentage divided by 100. Formula: Result = (X / 100) × Y

Example: What is 15% of 200? → (15 / 100) × 200 = 30

X is what % of Y?

Enter a value and a total. The calculator divides the value by the total and multiplies by 100. Formula: Result = (X / Y) × 100

Example: 45 is what % of 180? → (45 / 180) × 100 = 25%

% Change from X to Y

Enter the original value and the new value. The calculator finds the difference, divides by the absolute original value, and multiplies by 100. Formula: Result = ((Y - X) / |X|) × 100

Example: % change from 80 to 100 → ((100 - 80) / 80) × 100 = 25%

Tips for Accurate Calculations

✓ Always double-check which value is the 'part' and which is the 'whole'.
✓ For percentage change, the original value is always the denominator.
✓ Negative percentage change indicates a decrease.
✓ You can use decimals in all input fields for precise calculations.