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Percentage Calculator

Work out percentages, percentage change and reverse percentages.

What is X% of Y?

% of

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X is what percent of Y?

is what % of

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Percentage change

from to

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Reverse percentage

Find the value before a percentage was added or removed.

after %

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Quick Tool Overview

The Percentage Calculator answers the four percentage questions that actually come up: what is X percent of Y, X is what percent of Y, the percentage change between two numbers, and the original value before a percentage was added or removed. Every answer is shown with the arithmetic that produced it.

What it does
Solves percentages, percentage change and reverse percentages
You give it
Two numbers, or a number and a percentage
You get back
The answer plus the working behind it
Best for
Discounts, tax, grades, tips, margins and change over time
Calculators Free, unlimited use No sign-up Runs in your browser

About the Percentage Calculator

Four calculators covering the percentage questions that actually come up: what is X percent of Y, X is what percent of Y, the percentage change from one number to another, and the original value before a percentage was added or removed.

Each answer is shown with the arithmetic that produced it, so you can check the result rather than trusting it. The reverse calculator is the one worth knowing: to find a pre-VAT price you divide by 1.15, not subtract 15 percent, and getting that backwards is the most common percentage mistake in day-to-day business maths.

Key features of the Percentage Calculator

Four calculators in one

Percentage of a number, one number as a percentage of another, percentage change and reverse percentage each get their own panel.

The working is shown

Every result prints the arithmetic that produced it, so you can check the answer rather than trust it.

Reverse percentages done right

To find a pre-VAT price you divide by 1.15, not subtract 15 percent — the mistake this calculator exists to prevent.

Increase and decrease together

Percentage change reports direction as well as size, so a fall is not mistaken for a rise.

Instant results

Answers update as you type, with no submit button and no page reload.

How to use the Percentage Calculator

  1. 1

    Pick the right calculator

    Choose the panel that matches your question rather than rearranging the numbers yourself.

  2. 2

    Enter your numbers

    The result updates as you type.

  3. 3

    Check the working

    Each answer shows the formula it used, so you can verify or reuse it.

Frequently asked questions

Subtract the old value from the new one, divide by the old value, then multiply by 100. Going from 80 to 100 is (100-80)/80 x 100, a 25 percent increase.

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