PERCENTAGE CALCULATOR

Calculate percentages instantly and accurately.

CLIENT
100% client-side

Everything runs locally in your browser. Your data never leaves your device - no uploads, no servers, no tracking.

All processing happens directly on your machine using JavaScript. Close the tab and everything is gone. We literally never see your data.

Zero data transmission

Calculation mode

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Enter values to calculate
Formula:
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Percent of MODE

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FAVORITE MODE
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EFFICIENCY

How to use Percentage calculator

Simple, fast, and accurate percentage calculations

Full Documentation Docs
1

Choose mode

Select your calculation type

2

Enter values

Type your numbers

3

Get result

Instant accurate calculation

100% Private - Nothing stored
Real-time calculation
5 calculation modes
Works on all devices

Why choose our Percentage calculator?

The fastest, most accurate percentage tool online

Instant results

Real-time calculations as you type. No waiting, no delays, just instant accurate results.

Multiple calculation modes

Five different modes: find percentage of value, what percent is X of Y, percentage change, add/subtract percentage, and reverse calculation.

5 Calculation modes

From basic percentages to complex difference calculations - we've got you covered.

Formula display

See exactly how your result is calculated with step-by-step formulas.

Precision control

Adjust decimal places from 0 to 10 for the exact precision you need.

Copy formula

Copy calculation formulas separately. Perfect for documentation, reports, or sharing your math logic.

Frequently Asked Questions

Everything about percentage calculations

How do I calculate a percentage of a number?

To find a percentage of a number, multiply the number by the percentage and divide by 100. For example: 20% of 80 = (20 × 80) ÷ 100 = 16.

How do I calculate percentage increase?

Subtract the original value from the new value, divide by the original value, and multiply by 100. Formula: ((New - Old) ÷ Old) × 100.

What is the difference between percentage increase and percentage difference?

Percentage increase compares a change from an original value. Percentage difference compares two values without assuming one is the 'original'.

How do I find what percent one number is of another?

Divide the first number by the second number and multiply by 100. For example: 40 is what % of 200? (40 ÷ 200) × 100 = 20%.

What is reverse percentage calculation?

Reverse percentage finds the original value when you know a percentage and its result. For example: 80 is 20% of what? 80 ÷ (20 ÷ 100) = 400.

Is my data safe with this calculator?

Yes. Everything runs locally in your browser. Nothing is uploaded, nothing stored – your calculations stay 100% private.