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Kordu Tools
Math & Numbers Runs in browser Popular Updated 30 Mar 2026

Percentage Calculator

Calculate X% of Y, find what percentage X is of Y, or compute percentage increase and decrease. Results update as you type.

Enter both values to see the result.

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Formulae

X% of Y = (X / 100) * Y

X is what % of Y = (X / Y) * 100

% change = ((New - Old) / |Old|) * 100
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How to use Percentage Calculator

  1. Choose a calculation mode

    Select from 'X% of Y', 'X is what % of Y', 'X% more/less than Y', or '% change between two values' using the tabs.

  2. Enter your values

    Type both numbers into the input fields. The result updates automatically as you type — no button to press.

  3. Read the result

    The calculated percentage appears prominently. Percentage changes are color-coded: green for increases, red for decreases.

  4. Check the formula

    Expand the formula panel to see the exact equation used for your chosen mode.

Percentage Calculator FAQ

How do I calculate X% of a number?
Multiply the number by X and divide by 100. For example, 15% of 200 = (15/100) × 200 = 30.

How do I find what percentage X is of Y?
Divide X by Y and multiply by 100. Example: 25 is what % of 80? = (25/80) × 100 = 31.25%.

How is percentage change calculated?
Percentage change = ((new value − old value) / |old value|) × 100. A positive result is an increase; negative is a decrease.

How do I calculate a percentage increase?
New value = original × (1 + percentage/100). Example: 20% increase on 50 = 50 × 1.20 = 60.

How do I calculate a percentage decrease?
New value = original × (1 − percentage/100). Example: 15% decrease on 80 = 80 × 0.85 = 68.

What does 'X% more than Y' mean?
It means Y plus X percent of Y. Example: 20% more than 50 = 50 + (0.20 × 50) = 60.

How do I reverse a percentage (find the original value)?
If you know the result after a percentage change, original = result / (1 ± percent/100). Example: after 20% increase the price is 60, so original = 60/1.20 = 50.

Can I use this for discounts?
Yes. Use 'X% of Y' to find the discount amount, or 'X% more/less' to find the final price after a discount.

Can I use this for homework?
Yes. The formula panel shows the equation used so you can verify your method.

Is any data sent to a server?
No. All calculations happen entirely in your browser. Nothing is uploaded, stored, or logged.

Background

Solve every common percentage problem with four dedicated calculation modes. Find what X percent of Y is — essential for discounts, tips, and tax. Determine what percentage one number is of another — useful for test scores, market share, and ratios. Calculate the value after a percentage increase or decrease — handy for salary changes and price adjustments. Find the percentage change between two numbers — color-coded green for increases and red for decreases. Results update automatically as you type — no submit button needed. A quick-reference formula panel shows the equation behind each mode. Used by millions for homework, finance, shopping, and business calculations. No account, no ads in the tool area, and all processing runs entirely in your browser with nothing sent to any server.

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