Percentage Calculator
Calculate percentages, changes, and ratios easily
Percentage Calculator
Calculate what is X% of Y, or find the percentage one number is of another.
Basic Percentage Formula
To find X% of Y:
Result = (X/100) × Y
Example: 20% of 100 = (20/100) × 100 = 20
To find what % X is of Y:
Result = (X/Y) × 100%
Example: 20 is what % of 100? = (20/100) × 100 = 20%
Results
To calculate 20% of 100, multiply 20/100 by 100
Common Percentage Uses
Click on any button above to see a common percentage calculation. Update the amount in the main calculator to customize.
Key Features
Basic Percentages
Calculate percentages of numbers (X% of Y) and what percentage a number is of another.
Percentage Changes
Calculate increases and decreases between two values as percentages for business and data analysis.
Conversions
Convert between fractions, decimals, and percentages with ease for educational and practical applications.
Understanding Percentages
Learn how percentages work and their applications in daily life
What is a Percentage?
A percentage is a way to express a number as a fraction of 100. The word comes from the Latin "per centum," meaning "by the hundred." The percentage symbol % means "per hundred" - so 10% means 10 per 100, or 10/100, which equals 0.1.
Basic Percentage Formulas
To find X% of Y:
Result = (X/100) × Y
To find what percentage X is of Y:
Percentage = (X/Y) × 100%
To calculate percentage change:
% Change = ((Final - Initial) / |Initial|) × 100%
Common Percentage Applications
Discounts and Sales
When calculating discounts, you apply a percentage reduction to the original price:
Sale Price = Original Price - (Original Price × Discount%/100)
Example: 20% off a $80 item = $80 - ($80 × 20/100) = $80 - $16 = $64
Alternatively, you can calculate the sale price directly with: Original Price × (1 - Discount%/100)
Finance and Interest
Interest rates are expressed as percentages of the principal amount:
Simple Interest = Principal × (Rate%/100) × Time
Example: 5% interest on $1000 for 2 years = $1000 × (5/100) × 2 = $100
Compound interest is calculated using the formula: P × (1 + r/100)^t, where P is principal, r is rate, and t is time.
Markup and Margin
Markup is the percentage increase from cost to selling price:
Selling Price = Cost × (1 + Markup%/100)
Example: 50% markup on a $20 item = $20 × (1 + 50/100) = $20 × 1.5 = $30
Profit margin is the percentage of revenue that is profit:
Margin% = (Revenue - Cost) / Revenue × 100%
Example: For a $30 sale on a $20 item: ($30 - $20) / $30 × 100% = 33.33%
Academic Grading
Grades are often calculated as percentages of points earned vs. total possible points:
Grade% = (Points Earned / Total Points) × 100%
Example: 85 points out of 100 = (85/100) × 100% = 85%
Common grading scales convert percentage scores to letter grades, such as 90-100% = A, 80-89% = B, etc.
Did You Know?
The percentage symbol (%) emerged in the late Middle Ages, evolving from simply writing "per hundred" or "per cent" after numbers. Originally written as "per cento" in Italian, it was gradually abbreviated to "p cento," then "p.c." Eventually, this was further stylized into the % symbol we use today—the two small circles representing zeros in "100" with the diagonal line separating them.
Frequently Asked Questions
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