Choose a Percentage Calculation
Select whether you need percent of a number, percentage change, or percentage difference. The percentage calculator online supports the most common percent math tasks.
Percentage Calculator
Use this percentage calculator online to solve common percent math: find a percentage of a number, calculate percentage increase or decrease, compare two values, and work out percentage difference for shopping, reports, grades, and everyday planning.
Workspace
Use the tool below. Your inputs stay local when the tool supports browser-only processing.
What is X% of Y?
Last reviewed: · Testing methodology
Workflow
How to use the Percentage Calculator
Enter Your Numbers
Fill in the values for your calculation and the result appears instantly. The percentage calculator online also shows the formula so the answer is easy to understand.
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.
How this tool works
The component applies the formula for the selected mode, such as part / whole x 100 or (new - old) / 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, 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.
| Option | Best for | Trade-off |
|---|---|---|
| This browser tool | Quick, private, one-off work | Limited by browser memory and the documented feature set |
| Desktop or command-line tool | Batch jobs and repeatable automation | Requires installation and setup |
Verification
Reviewed by the Free Online Tools Nest Team on 2026-08-26. The interface, output path, and documented limitations were checked against the current implementation. See our testing methodology for the review process.
Read the testing methodologyUnderstand your result
Percentage Calculator — 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.