Percentage Calculator
Calculate percentage of a number, find what percent one value is of another, compute percentage change, or add and subtract percentages. Get step-by-step solutions instantly.
What is 20% of 150?
Answer: 30 (multiply 150 by 0.20)
45 is what % of 180?
Answer: 25% (divide 45 by 180, multiply by 100)
% change from 50 to 75?
Answer: +50% increase
Add 8% tax to $250?
Answer: $270 ($250 + $20 tax)
| Percentage | Decimal | Fraction | Of 100 | Of 200 | Of 500 |
|---|---|---|---|---|---|
| 5% | 0.05 | 1/20 | 5 | 10 | 25 |
| 10% | 0.10 | 1/10 | 10 | 20 | 50 |
| 15% | 0.15 | 3/20 | 15 | 30 | 75 |
| 20% | 0.20 | 1/5 | 20 | 40 | 100 |
| 25% | 0.25 | 1/4 | 25 | 50 | 125 |
| 33.33% | 0.3333 | 1/3 | 33.33 | 66.66 | 166.65 |
| 50% | 0.50 | 1/2 | 50 | 100 | 250 |
| 75% | 0.75 | 3/4 | 75 | 150 | 375 |
| 100% | 1.00 | 1 | 100 | 200 | 500 |
How to Calculate Percentages
A percentage represents a portion of a whole expressed as a fraction of 100. The word "percent" literally means "per hundred." Percentage calculations appear in everyday tasks such as calculating tips, figuring out discounts, understanding statistics, and comparing data. Our percentage calculator handles the four most common types of percentage problems.
Percentage of a Number
Result = (P / 100) × N
Find what a specific percentage of any number equals. For example, 15% of 300 = 45. This is the most common percentage calculation, used for tips, taxes, discounts, and commissions.
Number as Percentage of Another
% = (Part / Whole) × 100
Determine what percentage one number represents of another. For example, 36 is 45% of 80. Common for grades, test scores, completion rates, and proportional analysis.
Percentage Change
% Change = ((New − Old) / |Old|) × 100
Calculate the percentage increase or decrease between two values. If a stock goes from $40 to $52, the percentage increase is 30%. Used in finance, analytics, and performance tracking.
Add or Subtract Percentage
Result = N × (1 ± P/100)
Increase or decrease a number by a given percentage. Adding 8% tax to $250 gives $270. Subtracting 20% from $150 gives $120. Essential for pricing, budgeting, and tax calculations.
Real-World Percentage Applications
Percentages are used across finance, education, science, retail, and everyday life. Understanding how to calculate percentages quickly gives you an advantage in decision-making and analysis.
Finance & Business
- • Profit margin = (Revenue − Cost) / Revenue × 100
- • Interest rate calculations for loans and savings
- • Sales tax, VAT, and GST computation
- • Investment return on equity (ROI)
- • Year-over-year revenue growth
Education & Grades
- • Test scores: 42 out of 50 = 84%
- • GPA weighted percentage calculations
- • Attendance rates and completion percentages
- • Grade curves and class distributions
- • Scholarship eligibility thresholds
Everyday Life
- • Restaurant tip calculations (15%, 18%, 20%)
- • Shopping discounts and sale prices
- • Nutrition: daily value percentages on food labels
- • Battery and storage usage percentages
- • Cooking recipe scaling by percentage
Percentage Formulas & Mental Math Tips
With a few shortcuts, you can calculate most common percentages in your head. These mental math tips help you estimate quickly when a calculator is not available.
Quick Mental Math Shortcuts
- • 10%: Move the decimal one place left (10% of 250 = 25)
- • 5%: Find 10% and halve it (5% of 250 = 12.50)
- • 15%: Add 10% and 5% (15% of 250 = 37.50)
- • 20%: Find 10% and double it (20% of 250 = 50)
- • 25%: Divide by 4 (25% of 250 = 62.50)
- • 50%: Halve the number (50% of 250 = 125)
- • 1%: Move decimal two places left (1% of 250 = 2.50)
Converting Between Forms
- • % to Decimal: Divide by 100 (75% = 0.75)
- • Decimal to %: Multiply by 100 (0.125 = 12.5%)
- • Fraction to %: Divide then × 100 (3/8 = 37.5%)
- • % to Fraction: Put over 100, simplify (60% = 3/5)
- • Tip trick: X% of Y = Y% of X (8% of 50 = 50% of 8 = 4)
Frequently Asked Questions
How do you calculate a percentage of a number?
To calculate a percentage of a number, divide the percentage by 100 and multiply by the number. For example, to find 25% of 200: divide 25 by 100 to get 0.25, then multiply 0.25 by 200 to get 50. The formula is: Result = (Percentage / 100) × Number. This works for any percentage and any number, including decimals and negative values.
How do you find what percentage one number is of another?
To find what percentage one number is of another, divide the part by the whole and multiply by 100. For example, to find what percentage 45 is of 180: divide 45 by 180 to get 0.25, then multiply by 100 to get 25%. The formula is: Percentage = (Part / Whole) × 100. This is useful for grades, statistics, and comparing proportions.
How do you calculate percentage change?
To calculate percentage change, subtract the old value from the new value, divide by the absolute value of the old value, and multiply by 100. The formula is: % Change = ((New − Old) / |Old|) × 100. For example, if a price goes from $80 to $100: (100 − 80) / 80 × 100 = 25% increase. A positive result means an increase and a negative result means a decrease.
How do you add a percentage to a number?
To add a percentage to a number, calculate the percentage amount and add it to the original. For example, to add 15% to 200: first find 15% of 200, which is 30, then add it: 200 + 30 = 230. The shortcut formula is: Result = Number × (1 + Percentage/100). So 200 × 1.15 = 230. This is commonly used for calculating tax, tips, and markups.
What is the difference between percentage change and percentage difference?
Percentage change measures the relative change from an old value to a new value: ((New − Old) / Old) × 100. Percentage difference measures how two values differ relative to their average: (|A − B| / ((A + B) / 2)) × 100. Use percentage change when one value is clearly the 'before' and the other is 'after'. Use percentage difference when comparing two independent values with no inherent order.
How do you convert between percentages, decimals, and fractions?
To convert a percentage to a decimal, divide by 100 (25% = 0.25). To convert a decimal to a percentage, multiply by 100 (0.75 = 75%). To convert a percentage to a fraction, put the percentage over 100 and simplify (25% = 25/100 = 1/4). To convert a fraction to a percentage, divide the numerator by the denominator and multiply by 100 (3/4 = 0.75 × 100 = 75%).
Related Calculators
Discount Calculator
Calculate sale prices, percentage off, and savings.
Significant Figures Calculator
Count sig figs and evaluate math expressions properly.
Rounding Calculator
Round numbers to any place value with explanations.
Future Value Calculator
Calculate future value of investments with compound interest.
Share This Calculator
Found this tool helpful?
Help others discover it with one click.
Copy Link
Suggested hashtags: #percentage #Calculator #FreeTools #AICalculator