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Percentage Calculator

Calculate a percentage, ratio or percentage change.

Help & examples All tools
Calculation mode

What is X% of Y?
Calculators Local processing
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Last reviewed: · Testing methodology

Use this in a task

Choose a task to see when this tool helps and which steps you can skip.

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How to use

Enter two numbers and choose the calculation you need.

1

Choose a Percentage Calculation

Select whether you need percent of a number, percentage change, or what percent one value is of another. The percentage calculator online supports the most common percent math tasks.

2

Enter Your Numbers

Fill in the values for your calculation then press Calculate to show the result. The percentage calculator online also shows the formula so the answer is easy to understand.

3

Use the Result

Apply the percentage result to budgets, grades, growth rates, discounts, reports, or everyday math. You can clear the fields and run another calculation right away.

Examples and checks

How this tool works

The component applies the formula for the selected mode, such as part / whole x 100 or (new - old) / abs(old) x 100.

  • Engine: Direct JavaScript arithmetic for percentage modes
  • Supported input: finite numeric values
  • Output: percentage, part, total, or percentage-change result
Input
What is 15% of 80?
Output
12

Limits and questions

Inputs are processed in your browser. Analytics and advertising can make separate network requests.

Limits, edge cases, and troubleshooting

Use it for discounts, growth, marks, and proportions. Select the mode carefully because 'percent of' and 'percentage change' use different formulas.

  • Inputs must be valid finite numbers.
  • Division by zero is undefined; displayed rounding can hide additional decimal precision.

When to use another workflow

Use a spreadsheet for chained calculations, audit trails, scenario tables, currency rounding, and repeatable financial models.

Verification

Review record: 2026-08-26. See the documented behavior and limitations above, and the testing standards for the scope of review.

Testing methodology

Frequently asked questions

What can this percentage calculator online solve?
It can find a percentage of a number, calculate percentage increase or decrease, compare two values, and solve common percentage formulas used in school, work, and shopping.
Is the percentage calculator online free?
Yes. The calculator is free, runs in your browser, and does not require an account or upload any data.

Understand your result