Is this percentage calculator free to use?

Yes, it is completely free with no subscriptions and no sign-up required. Just open the page and start calculating.

Do you upload or store my numbers anywhere?

No. All calculations run entirely in your browser. Nothing you type is ever sent to a server or stored anywhere outside your device.

Does it work offline or without an internet connection?

Yes. Once the page is loaded, it works fully offline. No network requests are made during calculations.

How do I calculate the percentage increase between two numbers?

Use the third panel 'Percentage increase / decrease from X to Y'. Enter the original value in 'From' and the new value in 'To'. The result shows the percentage change and an increase/decrease badge instantly.

Can I find what percentage one number is of another?

Yes. Use the second panel 'X is what percent of Y?'. Enter both numbers and the percentage ratio is calculated and displayed in real time.

How do I work out the original price before a discount?

Reverse a percentage by dividing, not by subtracting. If an item costs 80 after 20% off, the original was 80 / 0.8 = 100. Taking 20% off 80 gives 64, a different and wrong answer. This is the single most common percentage mistake, and it is why "percent of" and "percent off" are separate calculations rather than one.

Why is a 50% rise followed by a 50% fall not back where it started?

Because each percentage applies to a different base. 100 rises by 50% to 150, then falls by 50% of 150 - which is 75, not 50 - landing at 75. Percentage changes never cancel out by simple addition, so a gain and an equal-sized loss always leave you slightly worse off than you began.

💯 Percentage Calculator

Solve any percentage problem instantly with three dedicated calculators: find X% of a number, determine what percent one number is of another, or calculate the percentage increase or decrease between two values—completely free and running entirely in your browser with no uploads or login required.

A percentage expresses a number as a fraction of 100; a percentage calculator handles a percent of a value, a ratio as a percent, and percent change.

What is X% of Y?

Result

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X is what percent of Y?

is what % of

Result

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Percentage increase / decrease from X to Y

From

Result

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Private by design. This tool runs entirely in your browser — nothing you enter is uploaded or stored, and it works offline.

About

This percentage calculator covers the three most common percentage questions people search for every day. All calculations happen locally in your browser using JavaScript—nothing is ever sent to a server, so your numbers stay completely private. It works fully offline, making it reliable even without an internet connection.

How to use

Choose the calculator panel that matches your question: 'X% of Y', 'X is what % of Y', or 'Percentage change from X to Y'.
Enter your numbers in the input fields. Results update live as you type—no need to press a button.
For percentage change, check the increase/decrease badge below the result to instantly see the direction of change.
Click the Copy button next to any result to copy it to your clipboard in one click.

FAQ

Is this percentage calculator free to use?: Yes, it is completely free with no subscriptions and no sign-up required. Just open the page and start calculating.
Do you upload or store my numbers anywhere?: No. All calculations run entirely in your browser. Nothing you type is ever sent to a server or stored anywhere outside your device.
Does it work offline or without an internet connection?: Yes. Once the page is loaded, it works fully offline. No network requests are made during calculations.
How do I calculate the percentage increase between two numbers?: Use the third panel 'Percentage increase / decrease from X to Y'. Enter the original value in 'From' and the new value in 'To'. The result shows the percentage change and an increase/decrease badge instantly.
Can I find what percentage one number is of another?: Yes. Use the second panel 'X is what percent of Y?'. Enter both numbers and the percentage ratio is calculated and displayed in real time.
How do I work out the original price before a discount?: Reverse a percentage by dividing, not by subtracting. If an item costs 80 after 20% off, the original was 80 / 0.8 = 100. Taking 20% off 80 gives 64, a different and wrong answer. This is the single most common percentage mistake, and it is why "percent of" and "percent off" are separate calculations rather than one.
Why is a 50% rise followed by a 50% fall not back where it started?: Because each percentage applies to a different base. 100 rises by 50% to 150, then falls by 50% of 150 - which is 75, not 50 - landing at 75. Percentage changes never cancel out by simple addition, so a gain and an equal-sized loss always leave you slightly worse off than you began.