Percentage calculator with formulas and steps

Calculate a percentage of a number, find the percentage between two values, or work out an increase or decrease with clear formulas and steps.

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Set your data

What do you want to calculate?

Value A

Value B

Values between −10¹² and 10¹². A denominator cannot be zero; percentage change requires a positive starting value. Results display up to 12 significant digits.

Result

Enter your values to see the result.

Download result

Compare percentages

Edit the values to compare them on two bars. Open the separate example to see two successive changes.

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How to use the tool

Edit the values to compare them on two bars. Open the separate example to see two successive changes.

Select a question, then fill in the two fields with their updated labels.
The result includes the formula using your numbers.

Method and principles

Percentage of a number: A × B ÷ 100.

Ratio: A ÷ B × 100.

Change: (B − A) ÷ A × 100.

Total from a part: A × 100 ÷ B.

Formula

p = \frac{A \times B}{100}

Method and limits

Values between −10¹² and 10¹². A denominator cannot be zero; percentage change requires a positive starting value. Results display up to 12 significant digits.

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Example

20% of 80 is 16. Going from 80 to 100 is a 25% increase; going back from 100 to 80 is a 20% decrease.

Practical example

Input

What do you want to calculate?: A% of B
Value A: 20
Value B: 80

Result

Calculation steps

Substitute the example values into the formula.
$p = \frac{20 \times 80}{100}$

(20) × (80) ÷ 100 = 16

Limits and checks

Limits and checks
Parameter	Value
Value A	≥ -1000000000000; ≤ 1000000000000
Value B	≥ -1000000000000; ≤ 1000000000000

PRACTICAL GUIDES

How to calculate reverse percentages and percentage change

Percentage changes depend on the starting value. Work through increases and decreases, reverse a change and see why equal percentages do not always cancel out.

Follow the steps