Percentage Calculator
What This Calculator Offers
This versatile percentage calculator solves three fundamental percentage problems with precision:
Basic Percentage Calculation – Find X% of any number
Percentage Proportion – Determine what percent X is of Y
Change Analysis – Calculate percentage increases/decreases
How to Use Each Calculator Function
1. “What is X% of Y?” (Basic Percentage)
Use case: Calculating discounts, tips, or commissions
How to:
Enter the percentage value (X)
Enter the base number (Y)
Click “Calculate”
Example:
What is 15% of 200?→ Result: 30
2. “X is what % of Y?” (Proportion)
Use case: Test scores, achievement rates, or ratio analysis
How to:
Enter the partial amount (X)
Enter the total amount (Y)
Click “Calculate”
Example:
75 is what % of 150?→ Result: 50%
3. “Change from Original to New” (Increase/Decrease)
Use case: Price changes, growth rates, performance changes
How to:
Enter the original value
Enter the new value
Click “Calculate”
Example:
Change from 80 to 100?→ Result: 25% increase
Key Features & Benefits
Triple-functionality in one compact tool Instant calculations with real-time results Decimal precision (results to 2 decimal places) Error handling (prevents division by zero) Mobile-friendly responsive design Visual clarity with color-coded buttons
Practical Applications
Financial Calculations
Shopping: Calculate 30% off $59.99
Investing: Determine 7.5% return on $10,000
Banking: Compute 2.5% interest on savings
Academic & Work Use
Grades: Find what percentage 87 is of 120 points
Business: Calculate 15% quarterly revenue growth
Statistics: Determine experimental success rates
Everyday Math
Tips: Compute 18% tip on $45 restaurant bill
Fitness: Track 5% body weight loss
Cooking: Adjust recipe by 150%
Technical Details
The calculator uses core JavaScript math operations:
Basic %:
(X / 100) * Y% Of:
(X / Y) * 100% Change:
((New - Original) / Original) * 100
All results display with 2 decimal places for consistency, automatically rounding while maintaining accuracy.
Why This Tool Stands Out
Unlike single-function percentage calculators, this tool:
Combines three essential calculations in one interface
Works offline after page load
Provides instant visual feedback
Features a clean, intuitive design
Includes error prevention for invalid inputs
Whether you’re managing finances, analyzing data, or just solving everyday math problems, this percentage calculator delivers fast, accurate results with just a few clicks.