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Percentage Calculator

Choose the question you are asking, enter two numbers and get the answer with the calculation written out. It covers the six common percentage problems: a percentage of a number, what percent one number is of another, percentage change, increasing and decreasing by a percentage, and finding the whole when you know a part and its percentage.

Calculate a percentage

%

Enter both numbers to see the answer.

How to use it

  1. Pick your question

    Choose from the list, for example “What is X% of Y?” or “Percentage change from X to Y”. The labels on the two fields change to match.

  2. Enter the numbers

    Type each number. You can use commas for thousands (1,250), a period for decimals and a leading minus sign. A % sign is accepted on percentage fields.

  3. Choose the rounding

    The answer is rounded to 2 decimal places by default. Change it if you need more or fewer.

  4. Read the answer and the working

    The answer appears with a one-line explanation and the formula using your numbers.

Example: how much did the price go up?

A subscription went from 40 to 46 a month. Choose “Percentage change from X to Y”, enter 40 and 46, and the tool reports an increase of 15%, worked out as ((46 − 40) ÷ 40) × 100.

The formulas

Each question uses one of these formulas, with X and Y as labelled on the form.

The six percentage questions with their formulas and examples
QuestionFormulaExample
What is X% of Y?(X ÷ 100) × Y15% of 200 = 30
X is what % of Y?(X ÷ Y) × 10025 is 12.5% of 200
Percentage change from X to Y((Y − X) ÷ |X|) × 10050 to 75 = +50%
Increase Y by X%Y × (1 + X ÷ 100)200 + 15% = 230
Decrease Y by X%Y × (1 − X ÷ 100)200 − 15% = 170
X is Y% of what number?X ÷ (Y ÷ 100)20 is 40% of 50

Limits and limitations

  • Percentage change from zero is undefined, so the tool asks for a non-zero starting value. When the starting value is negative the change is measured against its size, so going from −50 to −25 is reported as an increase of 50%.
  • Percentage points are not the same as percent: going from 10% to 12% is a rise of 2 percentage points but a 20% increase. Use the change calculation on the two numbers to get the second figure.
  • Answers are rounded for display only. Very small answers can round to zero at the chosen precision, in which case the tool says so.
  • Numbers must be written with a period for the decimal point and commas, if used, between groups of three digits.
  • Numbers above 999,999,999,999,999 are rejected.

Frequently asked questions

How do I calculate a percentage of a number?

Divide the percentage by 100 and multiply by the number. For example, 15% of 200 is 0.15 × 200 = 30. Choose “What is X% of Y?” and the tool does it for you.

What is the difference between percentage change and percentage points?

Percentage change compares two values as a proportion of the first. Percentage points are the plain difference between two percentages. A rate that moves from 10% to 12% has risen 2 percentage points, which is a 20% increase.

Why is a 50% increase followed by a 50% decrease not back to where I started?

The second percentage applies to a bigger number. 100 increased by 50% is 150, and 150 decreased by 50% is 75. To undo a 50% increase you need a decrease of about 33.33%.

Are my numbers stored or sent anywhere?

No. What you type is processed by JavaScript running in your browser and is not sent to a server. The page itself still loads from a web server like any website. This site can load advertising or analytics scripts, but only after you accept them in the cookie notice. They are separate from the tools, which never pass the files or text you work with to them.

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