Percentage Calculator
Calculate percentages, percentage changes, and what percent one number is of another.
Percentage Calculator
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How Percentage Calculations Work
Percentages express a number as a fraction of 100. "25% of 200" means 25/100 multiplied by 200, which equals 50. Percentage change measures how much a value has increased or decreased relative to its original amount. For instance, if a stock goes from $50 to $65, the percentage increase is (65-50)/50 = 30%.
This calculator handles three common percentage operations: finding what X% of Y is, determining what percentage X is of Y, and calculating the percentage change between two values.
Frequently Asked Questions
How is percentage change different from percentage difference?
Percentage change measures the relative change from an old value to a new value, using the old value as the base. Percentage difference compares two values without an inherent "before" and "after," typically using the average of the two values as the base. Percentage change is directional (increase or decrease), while percentage difference is always positive.
Why does a 50% decrease followed by a 50% increase not return to the original value?
Because each percentage is calculated on a different base. If you start with $100 and lose 50%, you have $50. A 50% increase on $50 gives you $75, not $100. To recover from a 50% loss, you actually need a 100% gain. The larger the loss, the disproportionately larger the gain needed to break even.
How do I calculate a percentage of a percentage?
Multiply the two percentages as decimals. For example, 20% of 50% is 0.20 x 0.50 = 0.10, or 10%. This comes up frequently with tax brackets, commission structures, and compounding scenarios.