Free Percentage Calculator

Calculate any percentage instantly — percentage of a number, percentage change, increase, decrease, tips, and discounts. No sign-up required.

✓ 100% Free ✓ Instant Results ✓ 6 Calculation Modes ✓ No Data Collected

What is X% of Y?

% of
Result

X is what percent of Y?

is what % of
Result

Percentage Change

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Percentage Change

Increase a Number by X%

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After Increase

Decrease a Number by X%

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After Decrease

Tip Calculator

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Tip & Total

Common Percentage Calculations

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Six Modes

Percentage of, what %, change, increase, decrease, and tip calculator.

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Instant

Results appear immediately. No loading or waiting.

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Private

All calculations run locally in your browser. Zero data sent.

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Mobile Ready

Works perfectly on phones, tablets, and desktops.

More Calculators Coming Soon

Compound interest, loan payments, BMI, and more — all free tools launching in 2026.

2026 Roadmap

How to Calculate Percentages

A percentage is simply a fraction of 100. To find X% of a number, multiply the number by X and divide by 100. For example, 25% of 200 = 200 × 25 ÷ 100 = 50. This is the fundamental formula behind all percentage calculations.

Percentage Change Formula

Percentage change measures how much a value has increased or decreased relative to the original value. The formula is: ((New Value - Old Value) / Old Value) × 100. A positive result means an increase; a negative result means a decrease. This is commonly used in finance, grades, sales metrics, and statistics.

When to Use a Percentage Calculator

Percentage calculations appear everywhere in daily life: figuring out tips at restaurants, calculating discounts while shopping, understanding tax rates, determining grade scores, analysing financial data, or computing profit margins. StealthEX makes all of these calculations instant and easy.

Understanding Tip Percentages

Common tip percentages vary by country and service quality. In the United States, 15-20% is standard for restaurants. Use the tip calculator mode to quickly figure out how much to tip and how to split the bill among friends.

Frequently Asked Questions

Yes, completely free. No accounts, no subscriptions, no hidden charges. All calculation modes are available to everyone.
StealthEX supports any number of decimal places in your input and displays results with up to 4 decimal places for maximum precision.
No. All calculations happen locally in your browser using JavaScript. Nothing is sent to any server. See our Privacy Policy for details.
Absolutely. StealthEX is fully responsive and works on mobile phones, tablets, and desktop computers.
Percentage change compares a new value to an old value (directional — it tells you if something went up or down). Percentage difference compares two values without implying direction, using the average of both as the base.
We're planning to release compound interest, loan payment, BMI, and unit conversion calculators throughout 2026. All tools will be free.