What is the formula to calculate a discount on a purchase?

Multiply the original retail price by the discount percentage (as a decimal), then subtract that discount amount from the original price. For example, a 20% discount on $80 is: $80 - ($80 × 0.20) = $64.

Can percentage change be negative?

Yes. A negative percentage change indicates a percentage decrease. For example, a fall from 100 to 75 represents a -25% decrease.

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Percentage Calculator

The Percentage Calculator is a versatile mathematical utility designed for students, shoppers, accountants, and engineers. Easily solve standard percentage queries like "What is 15% of 85?", calculate percentage increase or decrease between two numbers, compute discounts and sales tax, and convert any fraction into a percentage.

Calculate a percentage of a number:

Percentage (%)

Total Value (Y)

Quick %:

Formula Step: (15 ÷ 100) × 80 = 12.00

Calculation Result

15% of 80

Real-time calculation with infinite precision.

Core Percentage Formulas

How this mathematical and clinical model is calculated

Percentage = (Value / Total) × 100% | % Change = ((New - Old) / |Old|) × 100%

Percentages represent a fraction of 100. To find a percent of a number, multiply the value by the decimal equivalent (e.g. 20% = 0.20). To calculate percentage change or growth, divide the absolute difference by the original value and multiply by 100.

Step-by-Step Calculation Process:

X% of Y: Result = (X / 100) * Y

X is what % of Y: Result = (X / Y) * 100

Percentage Increase: Result = ((New - Old) / Old) * 100

Percentage Decrease: Result = ((Old - New) / Old) * 100

Key Capabilities & Features

5 calculation modes: X% of Y, What % is X of Y, % Change, Add/Subtract %, and Fractions

Real-time calculation with zero page reload

Step-by-step mathematical breakdown for educational clarity

One-click preset buttons (5%, 10%, 15%, 20%, 25%, 50%, 75%)

Convenient copy result button and calculation history

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Help & FAQ

Frequently Asked Questions: Percentage Calculator

Everything you need to know about tools in this section.

Subtract the original number from the new number, divide that difference by the original number, and multiply by 100. For example, if a price rises from $50 to $65: ((65 - 50) / 50) × 100 = 30% increase.