How to Calculate Percentage Online for Free
Percentage calculations come up constantly — discounts, tips, test scores, tax rates, price changes. This guide shows you how to use a free online percentage calculator to get accurate results instantly, without reaching for a phone or doing mental math.
The Three Types of Percentage Calculations
- Find X% of Y — "What is 15% of $85?" → multiply Y by X/100. Used for tips, discounts, tax amounts.
- X is what % of Y? — "42 out of 60 — what percentage is that?" → divide X by Y and multiply by 100. Used for test scores, completion rates.
- Percentage change — "Price went from $50 to $65 — what's the increase?" → (New − Old) ÷ Old × 100. Used for price tracking, growth rates.
The Formulas
X% of Y = Y × (X ÷ 100) X as % of Y = (X ÷ Y) × 100 % Change = ((New − Old) ÷ Old) × 100
Example: 15% of $85 = $85 × 0.15 = $12.75. A positive % change means an increase; negative means a decrease.
Step-by-Step Instructions
Open the Percentage Calculator
Navigate to the free Percentage Calculator. No account or download needed — it runs entirely in your browser.
Choose your calculation mode
Click the tab that matches what you need: "X% of Y" for finding a percentage amount, "X is what % of Y" for finding a percentage, or "% Change" for comparing two values.
Enter your values
Type the numbers into the input fields. The calculator updates the result live as you type — no button to press.
Read the result
The answer displays instantly with the formula used so you can verify the logic. Negative percentage change is shown in red; positive in green.
Copy or use the value
Click the copy button to copy the result to your clipboard, or simply read the number and use it in your work.
Common Use Cases
- Tip calculation: Find 18% of your restaurant bill instantly
- Discount shopping: See how much you save on a 30% off sale
- Grade calculation: Convert correct answers to a percentage score
- Tax estimation: Calculate VAT or sales tax on a purchase
- Price tracking: Find the percentage increase in your monthly utility bill
Calculate any percentage now
Three modes, live results, 100% browser-based — no uploads, no account.
Open Percentage Calculator