How do I find what percent one number is of another?

Use the "X is ?% of Y" mode: divide the part (X) by the total (Y) and multiply by 100. For example, 50 out of 200 is (50 ÷ 200) × 100 = 25%.

How is percent change calculated?

Percent change is the difference between the ending and starting values divided by the absolute value of the starting value, times 100. A positive result is an increase and a negative result is a decrease.

What happens if I enter zero as the total or starting value?

Division by zero is undefined, so the calculator returns a message such as "Cannot divide by zero" or "Cannot compute change from zero" and a result of 0 rather than producing an invalid number.

Does this calculator handle percentage decreases?

Yes. In "% Change" mode, entering a "To" value smaller than the "From" value yields a negative percentage, which represents a decrease. For instance, going from 200 to 150 gives −25%.

Percent Calculator

Percentage (%)

Of Value

Result50.0000

Description25% of 200 = 50

This percent calculator answers the three everyday percentage questions in one place: what a given percent of a number is, what percent one number is of another, and how much a value has changed in percentage terms. A mode switcher relabels the two inputs to match the question you are asking, so the same fields drive every calculation. Each result is paired with a plain-language description that restates the answer in context.

Formula

what-is: (X ÷ 100) · Y | is-what-percent: (X ÷ Y) · 100 | change: ((Y − X) ÷ |X|) · 100

X: First input — the percent, the part, or the starting value depending on mode
Y: Second input — the base value, the total, or the ending value depending on mode

How it works

Pick a mode: "X% of Y" to find a part of a whole, "X is ?% of Y" to express one number as a percentage of another, or "% Change" to measure growth or decline between two values.
Enter the two numbers. The input labels change with the mode (Percentage and Of Value, Value and Of Total, or From and To) so it is clear what each field means.
Read the numeric answer in the result card and the sentence description below it. Division-by-zero cases, such as a total of zero or a starting value of zero, return a safe explanatory message instead of an error.

Worked example

Using each of the three modes with the numbers 25, 50, 200, and 250.

X% of Y — 25% of 200: (25 ÷ 100) × 200 = 50.
X is ?% of Y — 50 is what percent of 200: (50 ÷ 200) × 100 = 25%.
% Change — from 200 to 250: ((250 − 200) ÷ 200) × 100 = 25%.

25% of 200 is 50; 50 is 25% of 200; and a move from 200 to 250 is a 25% increase.

Frequently asked questions

How do I find what percent one number is of another?: Use the "X is ?% of Y" mode: divide the part (X) by the total (Y) and multiply by 100. For example, 50 out of 200 is (50 ÷ 200) × 100 = 25%.
How is percent change calculated?: Percent change is the difference between the ending and starting values divided by the absolute value of the starting value, times 100. A positive result is an increase and a negative result is a decrease.
What happens if I enter zero as the total or starting value?: Division by zero is undefined, so the calculator returns a message such as "Cannot divide by zero" or "Cannot compute change from zero" and a result of 0 rather than producing an invalid number.
Does this calculator handle percentage decreases?: Yes. In "% Change" mode, entering a "To" value smaller than the "From" value yields a negative percentage, which represents a decrease. For instance, going from 200 to 150 gives −25%.

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