What is a Percentage Calculator?
A percentage calculator helps you solve common percentage problems quickly. Whether you need to find 15% of a total, determine what percentage a value represents, or calculate how much something increased or decreased, this tool handles it all.
Percentages appear everywhere - sales discounts, tax calculations, grade curves, statistical data, investment returns. Having quick access to accurate percentage calculations saves time and prevents errors.
Three Types of Percentage Calculations
Percentage of a number: What is X% of Y? Useful for calculating tips, discounts, and taxes.
What percent: X is what percent of Y? Useful for comparing values and analyzing data.
Percentage change: How much did a value increase or decrease? Essential for tracking growth, performance, and trends.
Common Uses
Percentages come up in everyday situations:
- Shopping: Calculating sale prices and discounts
- Finance: Interest rates, returns on investment, tax calculations
- School: Converting raw scores to percentages, calculating GPA
- Business: Profit margins, growth rates, market share
- Health: Body fat percentage, medication dosages by weight
The Math Behind Percentages
Percent means 'per hundred.' 25% literally means 25 per 100, or 0.25 as a decimal. This is why you divide by 100 when converting percentages to decimals.
All percentage calculations ultimately use this relationship: Part = (Percentage/100) × Whole. Rearranging gives you the other formulas.
Frequently Asked Questions
How do I calculate percentage of a number?
Multiply the number by the percentage and divide by 100. For example, 25% of 200 is (200 × 25) / 100 = 50.
How do I find what percentage one number is of another?
Divide the part by the whole and multiply by 100. For example, 50 is what percent of 200? (50 / 200) × 100 = 25%.
How do I calculate percentage increase or decrease?
Subtract the old value from the new value, divide by the old value, and multiply by 100. For increase from 100 to 125: ((125-100)/100) × 100 = 25% increase.
What's the difference between percentage and percentage points?
Percentage points are the arithmetic difference between percentages. If interest goes from 5% to 7%, that's a 2 percentage point increase, but a 40% relative increase.