Percentage Calculator
Choose a calculation mode and enter X and Y. The calculator can find X% of Y, determine what percent X is of Y, find the whole when X is Y% of it, or compare how much greater or less X is than Y.
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The main result uses the formula associated with the selected mode. The inputs remain the same, but X and Y represent different quantities depending on the question.
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How to Use This Calculator
Select the question that matches your problem, then enter X and Y. The labels explain how each value is used in the selected formula.
Formula & Methodology
The calculator supports five formulas: (1) X% of Y = (X ÷ 100) × Y; (2) X as a percent of Y = (X ÷ Y) × 100; (3) X is Y% of Whole, so Whole = X ÷ (Y ÷ 100); (4) percent greater = ((X − Y) ÷ Y) × 100; and (5) percent less = ((Y − X) ÷ Y) × 100.
Examples of the five percentage modes
20% of 150 = 30. 30 is 20% of 150. If 30 is 20% of a number, the whole is 150. 150 is 25% greater than 120. 90 is 25% less than 120.
Y must be greater than zero because modes 2 through 5 use Y in a denominator. For the reverse-whole mode, Y is the percentage rate and must also be greater than zero. Results depend on using the correct mode and reference value.
This calculator provides general mathematical results. Verify the selected mode and inputs before using a result for financial, tax, academic, or contractual decisions.
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- Reverse Percentage CalculatorFind the original value before a discount, reduction, markup, tax, or percentage increase was applied.
- What Percentage Is X of Y CalculatorFind what percentage one value represents of another value.
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Frequently Asked Questions
- How do I calculate X percent of Y?
- Divide X by 100 and multiply by Y. For example, 20% of 150 is (20 ÷ 100) × 150 = 30.
- How do I find what percent X is of Y?
- Divide X by Y and multiply by 100. For example, 30 is (30 ÷ 150) × 100 = 20% of 150.
- How do I find the whole when X is Y percent of it?
- Divide X by Y as a decimal. If 30 is 20% of a number, the whole is 30 ÷ 0.20 = 150.
- How do I calculate percent greater than?
- Subtract the reference value Y from X, divide by Y, and multiply by 100. The denominator must be the reference value.
- Why does the reference value matter?
- Percent comparisons are measured relative to a base. Changing the base changes the result, which is why a 25% increase and a 25% decrease do not automatically reverse each other.
Last updated 7/17/2026