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Percentage Calculator three ways

Pick the question you are asking, fill in X and Y, and see the answer with the percent written as a decimal and as a fraction.

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Answer

Enter your numbers or pick an example — the answer and the steps appear here instantly.

Three percentage questions, one form

  • What is X% of Y?

    Finds the part. For 15% of 80, turn 15% into 0.15 (or 3/20) and multiply, which gives 12.

  • X is what percent of Y?

    Finds the rate. For 12 out of 80, divide 12 by 80 to get 0.15, then multiply by 100 for 15%.

  • X is Y% of what?

    Finds the whole. If 12 is 15% of a number, divide 12 by 0.15 and the whole turns out to be 80.

What you see after Calculate

  • Decimal and fraction form

    The percent is converted both ways, so 12.5% shows up as 0.125 and as 1/8, and the arithmetic is done on that exact fraction.

  • A short worked outline

    Each step is numbered: convert the percent, multiply or divide, then state the result in the words of your question.

  • No floating-point surprises

    Exact fractions rule out errors of the 0.1 + 0.2 kind. When a result has an endless decimal, such as 1 as a percent of 3, the display shows a rounded value with ≈ in front and a Rounded tag.

  • Free and on your device

    The math runs inside your browser tab with no account, and the numbers you enter are never uploaded.

How to use the percentage calculator

  1. Choose the question

    Pick one of the three wordings from the Question menu, or click an example chip to load a ready-made case.

  2. Fill in X and Y

    Use whole numbers, decimals such as 7.5, fractions or negatives. Leave the % sign off, since the labels already say which value is the percent.

  3. Calculate and copy

    Read the answer and the outline, then copy the result. For a full explanation in sentences, use “Explain step by step”, keeping in mind the AI can make mistakes.

Doing percentages by hand: one equation, three unknowns

Every percentage question is the same equation: part = percent × whole, with the percent written as a decimal. What you are asked for decides which of the three you solve for.

Part: 15% of 80 = 0.15 × 80 = 12. Percent: 12 is 12 ÷ 80 = 0.15 of 80, which is 15%. Whole: if 12 is 15% of something, that something is 12 ÷ 0.15 = 80.

A mental shortcut: 10% of a number moves the decimal point one place left, so 10% of 80 is 8, and 5% is half of that, 4. Together, 15% of 80 is 12. Another handy fact is that X% of Y equals Y% of X, so 8% of 50 is the same as 50% of 8, which is 4.

Percents can exceed 100. 120 is 150% of 80, and 150% of 80 is 1.5 × 80 = 120. A percent over 100 simply means the part is larger than the whole you are comparing it with.

Frequently asked questions

Choose “X is what percent of Y?”, then enter the part as X and the total as Y. The calculator divides X by Y and multiplies by 100; 18 out of 24, for example, is 75%.

Yes. 2.5, 2,5, 5/2 and 2 1/2 are all read as the same exact value, and negative numbers are accepted too.

That symbol appears when the exact result has an endless decimal, for instance 2 as a percent of 3, which is 66.666…%. The value is rounded for display and tagged Rounded, while the outline keeps the exact fraction 200/3.

Use this page when you compare a part with a whole. If a value went from one number to another and you want the rise or fall in percent, the percent change calculator is the right tool.

Nothing on the Pro plans* (*fair use: up to 300 runs a day, counted across the writing, study and code tools). Without a plan, each explanation takes 2 credits, and if you are signed out you can read the first part for free. The calculator itself is always free.

Use it to verify your own working and to learn how to set the problem up. Your teacher's or school's policy on calculators and AI tools decides what is allowed on graded work.

Other percent and ratio tools

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