Percentage Calculator — Find X% of Y Instantly & Free

The Percentage Calculator helps you quickly work out five common percentage scenarios: finding a percentage of a number, determining what percent one number is of another, calculating the percentage change, finding the percentage difference between two values, and adding or subtracting a percentage. Whether you are shopping, working with data, or handling finances, this tool delivers fast and accurate results entirely in your browser.

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What Are Percentages?

A percentage is a way of expressing a number as a fraction of 100. The word "percent" comes from the Latin per centum, meaning "by the hundred." Percentages simplify comparisons by standardizing proportions, making it easy to understand relationships across different scales.

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How to Use This Calculator

1
Choose your calculation type: Click one of the five tabs — % of Y, X is what % of Y, % Change, % Diff, or +/- %.
2
Enter your numbers: Fill in the two input fields for your selected mode. Results update in real-time as you type.
3
Review the result: The result card shows the final answer, the formula used, and a progress visualization.
4
Copy or reset: Use the Copy Value or Copy Formula buttons, or click Reset to start over.

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Percentage Formulas

X% of Y

Result = (X ÷ 100) × Y

X is what % of Y

Result = (X ÷ Y) × 100

% Change

Change = ((New − Old) ÷ |Old|) × 100

% Difference

Diff = (|A−B| ÷ ((A+B) ÷ 2)) × 100

Add/Subtract %

Result = N × (1 ± P ÷ 100)

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When to Use Each Mode

% of Y Shopping discounts, tax calculations, commission rates, tip amounts

X is what % of Y Test scores, survey results, budget allocation, performance metrics

% Change Stock market returns, population growth, price changes, sales performance

% Diff Product price comparison, salary benchmarks, A/B testing analysis

+/- % Adding tax to a bill, applying discounts, calculating markup or margin

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Why Percentages Matter

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Financial Decisions
Interest rates, investment returns, loan terms, and tax obligations all rely on percentages.

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Shopping & Discounts
Sales, coupons, and promotions are expressed as percentages. Calculate real savings instantly.

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Academic Assessment
Grades, test scores, and academic progress are typically measured in percentages.

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Data Analysis
Percentages provide a common scale for comparing proportions across different sample sizes.

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Health & Nutrition
Daily values on nutrition labels, medical statistics, and body metrics use percentages.

Frequently Asked Questions

How do I calculate X% of Y?

Multiply X by Y and divide by 100. For example, 15% of 200 is (15 × 200) ÷ 100 = 30. Our calculator does this instantly.

How do I find what percent X is of Y?

Divide X by Y and multiply by 100. For example, 30 out of 200 is (30 ÷ 200) × 100 = 15%. The calculator handles this in one click.

What's the difference between % Change and % Diff?

% Change tracks a single value over time (old vs new). % Difference compares two separate values using their average. For example, going from 100 to 150 is a 50% increase, but the difference between 100 and 150 is 40%.

How is percentage change calculated?

Subtract the old value from the new, divide by the absolute old value, then multiply by 100. A positive result means an increase; negative means a decrease.

Is this tool free?

Yes, completely free with no subscriptions, usage limits, or hidden fees.

Is my data private?

Absolutely. All calculations happen locally in your browser. Your numbers never leave your device.

🔒 Privacy Note: This tool processes all data locally in your browser. No information is ever uploaded to our servers, ensuring your data remains 100% private.

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