Percentage Calculator
Calculate percentages easily — find what percent of a number is, percentage change, and more.
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What Is a Percentage Calculator?
This percentage calculator solves three types of percentage problem in one tool. Enter two values and get the result instantly. Use it for discounts, exam scores, tax rates, tips, or any situation involving proportions.
Percentages represent a fraction of 100. The word itself comes from the Latin per centum meaning "by the hundred." Convert between percentages, decimals, and fractions by moving the decimal point two places or dividing by 100.
Type a number and a percentage to find the result. Reverse the inputs to find what percentage one number is of another. Switch to percentage-change mode to measure increases or decreases between two values.
How Do You Use This Percentage Calculator?
Choose your calculation type: find a percentage of a number, find what percentage one number is of another, or calculate percentage change between two values.
- Select the calculation type: percentage of a number, percentage one value is of another, or percentage change.
- Enter the first value in the field provided.
- Enter the second value or percentage.
- Click Calculate to see the result.
- Read the answer displayed below the form.
- Click Reset to start a new calculation.
How Does the Percentage Calculator Formula Work?
The formula used: Percentage = (Part / Whole) × 100
Find a percentage of a number: multiply the number by the percentage and divide by 100.
Result = Number × (Percentage / 100)
Find what percentage A is of B: divide A by B and multiply by 100.
Percentage = (A / B) × 100
Calculate percentage change between an old value and a new value: subtract the old from the new, divide by the old, and multiply by 100.
Change = ((New - Old) / Old) × 100
A positive result indicates an increase. A negative result indicates a decrease.
What Are Some Example Calculations?
What is 15% of 200? Answer: 200 × 0.15 = 30. What percentage is 45 of 180? Answer: (45 / 180) × 100 = 25%.
A shirt originally costs £80 and is reduced by 25%.
Discount = 80 × (25 / 100) = 20. Sale price = 80 − 20 = 60.
The discount is £20. The sale price is £60.
A student scores 42 out of 56 on a test.
Percentage = (42 / 56) × 100 = 75.
The student scored 75%.
A rent payment rises from £950 to £1,045 per month.
Change = ((1045 − 950) / 950) × 100 = 10.
The rent increased by 10%.
When Should You Use a Percentage Calculator?
Use this calculator whenever you need to work with proportions expressed as parts per hundred. Common situations include applying a discount to a price, finding a test or exam score, calculating VAT, or measuring how much a value has risen or fallen.
Businesses use percentage calculations for profit margins, sales tax, and commission rates. Students use them for grade boundaries and statistics coursework. Enter your numbers above and get the answer in under a second.
What Do These Terms Mean?
How Do the Options Compare?
| Percentage | Decimal | Fraction |
|---|---|---|
| 1% | 0.01 | 1/100 |
| 5% | 0.05 | 1/20 |
| 10% | 0.10 | 1/10 |
| 12.5% | 0.125 | 1/8 |
| 20% | 0.20 | 1/5 |
| 25% | 0.25 | 1/4 |
| 33.33% | 0.3333 | 1/3 |
| 50% | 0.50 | 1/2 |
| 66.67% | 0.6667 | 2/3 |
| 75% | 0.75 | 3/4 |
| 100% | 1.00 | 1/1 |
What Are the Best Tips to Know?
- Convert a percentage to a decimal by dividing by 100. Move the decimal point two places left.
- Reverse the calculation to check your answer. If 20% of 150 is 30, then 30 / 150 × 100 should return 20.
- Use percentage change — not a simple difference — when comparing two values over time.
- Remember that a 50% decrease followed by a 50% increase does not return to the original value.
- Round percentages to 1 or 2 decimal places for most practical purposes.
What Mistakes Should You Avoid?
- Dividing by the new value instead of the original value when calculating percentage change.
- Forgetting to multiply by 100 after dividing, giving a decimal instead of a percentage.
- Adding successive percentages directly. A 20% rise then a 10% rise is not a 30% rise overall.
- Confusing percentage points with percentages. A rate rising from 5% to 7% is a 2 percentage-point increase but a 40% increase.
Frequently Asked Questions
How do I calculate a percentage of a number?
Multiply the number by the percentage divided by 100. For example, 20% of 150 = 150 × (20 / 100) = 30.
How do I calculate percentage increase?
Percentage increase = ((New Value - Original Value) / Original Value) × 100. For example, from 50 to 65: ((65 - 50) / 50) × 100 = 30% increase.
How do I convert a fraction to a percentage?
Divide the numerator by the denominator and multiply by 100. For example, 3/4 = 0.75 × 100 = 75%.
How do I convert a percentage to a decimal?
Divide the percentage by 100. Move the decimal point two places to the left. For example, 45% becomes 0.45 and 7.5% becomes 0.075.
What is the difference between percentage and percentage points?
Percentage points measure the arithmetic difference between two percentages. If interest rises from 3% to 5%, that is 2 percentage points but a 66.7% increase in relative terms.
How do I find the original price before a discount?
Divide the discounted price by (1 minus the discount rate as a decimal). A £60 item after 25% off: £60 / 0.75 = £80 original price.
How do I calculate percentage decrease?
Percentage decrease = ((Original Value - New Value) / Original Value) × 100. From 80 to 60: ((80 - 60) / 80) × 100 = 25% decrease.
Can percentages exceed 100%?
Yes. A value that doubles shows a 100% increase. A value that triples shows a 200% increase. Percentages above 100% indicate the result is larger than the reference value.
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