Percentage Calculator
Solve percentage-of, what-percent and percentage-change calculations.
Solve three common percentage questions
Calculate a percentage of a number, determine what percent one number is of another, or calculate percentage change.
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Percentage formulas used
- P% of X: P ÷ 100 × X.
- A is what percent of B: A ÷ B × 100.
- Percentage change: (new − old) ÷ |old| × 100.
Why percentage change uses the old value
Percentage change measures the difference relative to the starting point, so the original value is the denominator. The tool uses the absolute value of the starting number to keep the sign focused on direction of change.
Percentage points are different
If a rate rises from 20% to 25%, that is an increase of 5 percentage points, but a 25% relative increase because 5 ÷ 20 = 25%.
Zero needs special handling
“What percent is A of zero?” and percentage change from zero have undefined division in these formulas, so the calculator displays a dash rather than an infinite or misleading result.
Frequently asked questions
How do I calculate 20% of a number?
Multiply the number by 20 divided by 100, which is the same as multiplying by 0.20.
What is the difference between percent and percentage points?
Percentage points describe the arithmetic difference between two percentages; percent change describes the relative change from the original value.
Why is change from zero unavailable?
The standard percentage-change formula divides by the original value, so a zero starting value creates division by zero.
Can percentages be over 100%?
Yes. A ratio can exceed 100% when the numerator is greater than the denominator.