Percentage Calculator
Calculate percentages easily. Find percentage of a number, percentage change, percentage difference, and more. Free online percentage calculator.
What is X% of Y?
X is what percent of Y?
Percentage Change
What is Percentage Calculator?
A percentage calculator performs the most common percentage operations that people need in daily life, school, business, and finance. Percentages express proportional relationships — they tell you how one quantity relates to another on a scale of 0 to 100. This tool handles three primary calculations: finding what percentage one number is of another (e.g., 25 out of 200 = 12.5%), finding a percentage of a number (e.g., 15% of 350 = 52.5), and calculating percentage change between two values (e.g., price went from $80 to $100 = 25% increase). These calculations appear constantly in discounts, taxes, tips, grades, statistics, and financial analysis.
How It Works
Enter your numbers into the appropriate fields based on what you need to calculate. For 'X% of Y': the tool multiplies Y by X and divides by 100. For 'X is what % of Y': it divides X by Y and multiplies by 100. For percentage change: it calculates (New - Old) / Old × 100, where positive results indicate increases and negative results indicate decreases. For percentage difference: it uses |A - B| / ((A + B) / 2) × 100. Results calculate instantly as you type. The tool also handles edge cases like division by zero and displays results with appropriate decimal precision.
Examples
15% of 250
37.5
Old: 80, New: 100
25% increase
Price after a 25% increase: 150
Original price: 150 / 1.25 = 120 (Subtracting 25% from 150 gives 112.50, which is wrong.)
Tips & Best Practices
A 50% increase followed by a 50% decrease does NOT return to the original. $100 + 50% = $150, then - 50% = $75.
To mentally calculate 15%: find 10% (move decimal), then add half of that for the extra 5%.
Percentage points and percentages are different: going from 10% to 15% is a 5 percentage point increase, but a 50% relative increase.
Common Use Cases
- •Calculating sale discounts — finding the final price after a 20% or 30% discount
- •Computing tax amounts — determining sales tax, income tax, or VAT on purchases
- •Figuring out tips at restaurants based on the bill total and desired tip percentage
- •Calculating grade percentages — what score you need on a final exam to reach a target grade
- •Analyzing financial performance — year-over-year revenue growth or decline percentages
- •Computing profit margins, markups, and commission rates in business contexts
Frequently Asked Questions
How do I calculate percentage of a number?▼
To find X% of Y: multiply Y by X and divide by 100. For example, 25% of 200 = 200 × 25 / 100 = 50. The calculator does this instantly as you type.
How to calculate percentage change?▼
Percentage change = ((New Value - Old Value) / Old Value) × 100. A positive result means increase, negative means decrease. For example, going from $80 to $100 is a 25% increase.
Can I calculate percentage difference?▼
Yes, percentage difference = |A - B| / ((A + B) / 2) × 100. This measures the relative difference between two values without designating one as 'old' and one as 'new'.
What's the difference between percentage change and percentage difference?▼
Percentage change measures how much a value increased or decreased relative to the original. Percentage difference measures how two values compare relative to their average — it doesn't imply one came before the other.
How do I reverse a percentage?▼
To find the original price before a discount: divide the discounted price by (1 - discount/100). For example, if an item costs $80 after 20% off: $80 / (1 - 0.20) = $80 / 0.80 = $100 original price.
How do percentages work with compounding?▼
Compound percentages don't simply add up. A 10% increase followed by a 10% decrease doesn't return to the original — it results in a 1% net decrease. For compound calculations, use our Compound Interest Calculator.
Why doesn't a 50% increase followed by a 50% decrease return to the start?▼
Because each change is applied to a different base. £100 plus 50% is £150, and 50% of £150 is £75, not £100. To reverse a percentage increase you divide by (1 + rate) rather than subtracting the same percentage.
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