What happens if the original value is zero in percentage change?

Mathematically, percentage change cannot be calculated when the starting value is zero because division by zero is undefined. An increase from 0 to any positive number represents an infinite percentage growth.

Can I use negative numbers?

Yes, our calculator supports negative inputs for financial growth, stock market loss tracking, and negative temperature variations.

Calculators100% Client-Side • Zero Data Storage

Free Online Percentage Calculator

Solve percentage equations, calculate price discounts, and compute percentage increases or decreases with step-by-step formulas.

Percentage (%)

Of Number

Calculated Result

Formula: (15 ÷ 100) × 240 = 36

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How to Use the Free Online Percentage Calculator

Select Calculation Mode

Choose between 'What is X% of Y?', 'X is What % of Y?', 'Percentage Change (Increase/Decrease)', or 'Discount & Savings'.

Input Values

Enter your numbers in the designated input fields. Results compute in real time as you type.

Review Result & Mathematical Formula

Check the calculated result and review the step-by-step mathematical formula used to obtain the answer.

Standard Percentage Formulas & Practical Examples

1. Percentage of a Number ($X\%$ of $Y$):
Formula: (X ÷ 100) × Y
Example: 20% of 150 = (20 ÷ 100) × 150 = 30.

2. Percentage Proportion ($X$ is what $\%$ of $Y$):
Formula: (X ÷ Y) × 100
Example: 25 is what % of 200 = (25 ÷ 200) × 100 = 12.5%.

3. Percentage Increase / Decrease:
Formula: ((New Value - Old Value) ÷ |Old Value|) × 100
Example: Price changes from $100 to $130 = ((130 - 100) ÷ 100) × 100 = +30% increase.

4. Discount & Savings:
Final Price = Original Price - (Original Price × Discount% ÷ 100)

Frequently Asked Questions

Subtract the new value from the original value, divide that difference by the original value, and multiply the result by 100. For example, if a price drops from $80 to $60: ((80 - 60) ÷ 80) × 100 = 25% decrease.

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Browser Privacy Promise

This tool processes your inputs strictly using modern JavaScript inside your local web browser. None of your data, text, or calculations are transferred or logged to any remote server.