Percentage Calculator

Percentage Calculator: calculate percent of a number, what percent one value is of another, percent change, and percentage difference.

This percentage calculator covers the three most common percentage questions in one place. You can find A as X% of B, calculate how much bigger or smaller B is than A, and measure the percentage difference between two values.

The first two modes also work in reverse. That means you can solve for A, B, or X% by entering the other two values. The percentage difference mode is intentionally one-way, because the symmetric formula does not give a unique reverse solution for A or B.

$$A = \frac{X\% \times B}{100}$$

$$A = \frac{X\%\times B}{100}$$

$$X\% = \frac{A}{B} \times 100$$

$$X = \frac{A}{B}\times100$$

$$B = \frac{A \times 100}{X\%}$$

$$B = \frac{A\times100}{X\%}$$

$$A = \frac{B \times 100}{100 + X\%}$$

$$A = \frac{B\times100}{100+X\%}$$

$$X\% = \frac{B - A}{A} \times 100$$

$$X = \frac{B-A}{A}\times100$$

$$B = A + \frac{X\% \times A}{100}$$

$$B = A + \frac{X\%\times A}{100}$$

$$X\% = \frac{|A - B|}{\left(\frac{A + B}{2}\right)} \times 100$$

$$X = \frac{|A-B|}{(A+B)/2}\times100$$

Initial Data

A is X% of B

B is X% bigger/smaller than A

Percentage difference between A and B

Tip: Choose, if you would like to find A, B or X and insert the other two values!

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Percentage Calculator FAQ

What can this percentage calculator calculate?
This calculator can answer three common percentage questions. It can calculate A as X% of B, find how many percent bigger or smaller B is than A, and calculate the percentage difference between A and B.

How do I calculate a value as a percentage of another value?
Use the first mode, A is X% of B. This covers questions such as What is 25% of 100?, 25 is what percent of 100?, and 25 is 25% of what number?. The core formula is X% = (A / B) × 100.

How do I calculate percent increase or decrease?
Use the second mode, B is X% bigger/smaller than A. It uses X% = ((B - A) / A) × 100. A positive result means B is bigger than A, and a negative result means B is smaller than A.

What is the difference between percent change and percentage difference?
Percent change compares a new value with a starting value, so direction matters. Percentage difference is symmetric and compares the gap between two values relative to their average. This calculator uses X% = |A - B| / ((A + B) / 2) × 100 for percentage difference.

Why can I only solve for X% in percentage difference mode?
Because percentage difference is symmetric, the same result can come from more than one pair of input values. That means reverse-solving uniquely for A or B would be ambiguous, so this mode always returns X% as the result.

» Percentage Calculator

Percentage Calculator

Initial Data

See also:

Percentage Calculator FAQ