Percentage Calculator

Calculate percentages, percentage change, increase/decrease, and reverse percentages.

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What is X% of Y?

%
15% × 200 = 30

What is a Percentage Calculator?

A percentage calculator helps you compute percentages quickly and accurately. It supports common percentage calculations used in finance, shopping, statistics, and everyday life.

This tool features:

  • Four calculation modes — Percent of a number, proportion, change, and reverse percentage.
  • Formula display — See how each result is calculated step by step.
  • Instant results — Results update in real-time as you type.

How to Use

  1. Select a mode — Click one of the four calculator modes above.
  2. Enter values — Fill in the input fields for the selected mode.
  3. Read the result — The result updates automatically as you type.

Frequently Asked Questions

How do I calculate percentage of a number?

Multiply the number by the percentage divided by 100. For example, 15% of 200 = 200 × 15/100 = 30. Use the "What is X% of Y?" mode.

How do I calculate percentage change?

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

What is reverse percentage?

Reverse percentage finds the original number when you know a part and its percentage. For example, if 30 is 15% of a number, the number is 30 / (15/100) = 200.

Is this tool free to use?

Yes. All processing happens entirely in your browser. No data is sent to any server.