Percentage Calculator
Calculate percentages, ratios, and proportions easily
Our percentage calculator helps you solve various percentage problems, including finding percentages of numbers, calculating percentage changes, and converting between fractions, decimals, and percentages. Whether you're calculating discounts, tax rates, or academic grades, this tool provides quick and accurate results.
Common Conversions
What is a Percentage?
A percentage is a number expressed as a fraction of 100. The word comes from the Latin "per centum," meaning "by the hundred." For example, 45% means 45 out of 100, or 45/100.
Key Concepts:
- 100% represents the whole amount
- 50% is half or one-second of the total
- 25% is one-quarter of the total
- 1% is one-hundredth of the total
Common Percentage Calculations
Finding a Percentage
To find what percentage A is of B:
(A ÷ B) × 100 = percentage
Example: 20 is what % of 80?
(20 ÷ 80) × 100 = 25%
Finding a Value from Percentage
To find what value is P% of X:
(P ÷ 100) × X = value
Example: What is 25% of 80?
(25 ÷ 100) × 80 = 20
Real-World Applications
Shopping & Discounts
- • Calculate sale prices
- • Compare discounts
- • Figure tax amounts
- • Determine tips
Academic Use
- • Grade calculations
- • Test scores
- • Class averages
- • Progress tracking
Business
- • Profit margins
- • Growth rates
- • Market share
- • Commission rates
Understanding Percentage Change
Percentage change measures how much a value has increased or decreased relative to its original value.
Formula:
((New Value - Original Value) ÷ Original Value) × 100
Example: Price changes from $80 to $100
((100 - 80) ÷ 80) × 100 = 25% increase
Percentage Tips and Tricks
Quick Mental Math
- • 10% = Move decimal point left once
- • 1% = 10% ÷ 10
- • 5% = Half of 10%
- • 15% = 10% + 5% (useful for tips)
- • 25% = Quarter or divide by 4
Common Conversions
- • 1/4 = 25%
- • 1/3 ≈ 33.33%
- • 1/2 = 50%
- • 2/3 ≈ 66.67%
- • 3/4 = 75%