Calculating percentages (X% of Y, percent change, etc.) usually means reaching for a calculator or a spreadsheet. The Percentage Calculator does it in the browser: enter two numbers and the operation and get the result—no sign-up and no data sent to a server.
What calculations are available?
Percentage Calculator supports X% of Y, what % is X of Y, percentage increase/decrease, and percentage difference. You can use "X% of Y" mode to calculate tips, discounts, or any percentage. Input: two numbers and the operation (e.g. what is 20% of 50, or what % is 10 of 40). Calculation runs in your browser; your numbers are not stored or sent. Use it for tips, discounts, tax, markup, or any problem involving percent of a number or percent change. A negative percentage change means a decrease: (New − Old) ÷ Old × 100; if new is smaller, the percentage is negative.
Key Features
- Modes — X% of Y, what % is X of Y, percentage increase/decrease, percentage difference.
- Tips and discounts — Yes. Use "X% of Y" mode to calculate tips, discounts, or any percentage.
- Input — Two numbers and the operation (e.g. what is 20% of 50, or what % is 10 of 40).
- Privacy — No. Your data is not sent to a server. Calculation runs in your browser. Your numbers are not stored or sent.
- No account — Use as often as you need without sign-up.
- Negative change — A negative result means a decrease. (New − Old) ÷ Old × 100; if new is smaller, the percentage is negative.
How to Use the Percentage Calculator
- Open the Percentage Calculator tool.
- Choose calculation type (e.g. X% of Y, percent change). Enter the numbers. View the result.
- Use the "Use tool" button on the docs page if you are reading this from the documentation.
Real Use Cases
- Tips — Bill × tip %. Use "X% of Y" (e.g. 18% of 45). Split total with Tip Calculator if needed.
- Discounts — Price × (1 − discount %). Or "X% of Y" for discount amount. Compare with Discount Calculator for full workflow.
- Tax and markup — Add or remove tax/markup. Percent of a number and percent change.
- Percent change — (New − Old) ÷ Old × 100. Use for growth, decline, or A/B metrics.
- What % is X of Y — e.g. 25 of 200 = 12.5%. Use for proportions and ratios.
- Teaching — Demonstrate percent concepts. Multiple modes in one place.
Why Use the Percentage Calculator Instead of Alternatives?
- vs. BMI Calculator — BMI Calculator is for BMI. This tool is for general percent math. Different purpose.
- vs. Loan Calculator — Loan Calculator is for loans. This tool is for percentages. Use both as needed.
- vs. Unit Converter — Unit Converter converts units. This tool calculates percentages. Different domain.
- vs. Manual — No formula to remember. Choose mode, enter numbers, copy result.
A negative result means a decrease. (New − Old) ÷ Old × 100; if new is smaller, the percentage is negative.
- Shopping — Discounts and tax. Quick percent of a number.
- Work — Markup, margin, percent change. One tool, multiple modes.
- School — Practice percent problems. See step or result as needed.
Common Mistakes
- Percentage change negative — A negative result means a decrease. (New − Old) ÷ Old × 100; if new is smaller, the percentage is negative.
- Wrong order — "What % is X of Y" means X ÷ Y × 100. Swap X and Y if you meant the other way.
- Expecting loan/tip-specific — This tool is general percent. For tip + split use Tip Calculator. For loans use Loan Calculator.
- Forgetting to copy — The result is not saved. Copy before closing the tab.
Frequently Asked Questions
What calculations are available?
X% of Y, what % is X of Y, percentage increase/decrease, and percentage difference.
Can I calculate tips?
Yes, use 'X% of Y' mode to calculate tips, discounts, or any percentage.
Two numbers and the operation (e.g. what is 20% of 50, or what % is 10 of 40).
Is my data sent to a server?
No. Calculation runs in your browser. Your numbers are not stored or sent.
When should I use a percentage calculator?
Use it for tips, discounts, tax, markup, or any problem involving percent of a number or percent change.
Why is my percentage change negative?
A negative result means a decrease. (New − Old) ÷ Old × 100; if new is smaller, the percentage is negative.
Percentage Calculator gives you percent results in seconds: choose mode, enter numbers, view result. No account, no server round-trip. For BMI use BMI Calculator, for loans use Loan Calculator, and for units use Unit Converter.
Use the Percentage Calculator tool to calculate percentages.