Percentage Calculator

Calculate percentages, percentage increase/decrease, and more with our easy-to-use calculator.

Result

15

15% of 100 is 15

Common Percentages

10% of 10010
25% of 10025
50% of 10050
75% of 10075
100% of 100100
150% of 100150
200% of 100200

How to Calculate Percentage of a Number

To find X% of Y, multiply Y by X/100.

15% of 100 = (15/100) × 100 = 0.15 × 100 = 15

Understanding Percentages

A percentage is a number expressed as a fraction of 100. The word comes from the Latin "per centum," meaning "by the hundred." Percentages are used to express how large or small one quantity is relative to another quantity.

Common Percentage Calculations

Finding the Percentage of a Number

To find X% of Y, multiply Y by X/100. For example, to find 15% of 80:

15% of 80 = (15/100) × 80 = 0.15 × 80 = 12

Finding What Percentage X is of Y

To find what percentage X is of Y, divide X by Y and multiply by 100. For example, to find what percentage 12 is of 80:

12 is what % of 80? = (12/80) × 100 = 0.15 × 100 = 15%

Calculating Percentage Increase or Decrease

To find the percentage increase or decrease from X to Y:

Percentage change = ((Y - X) / X) × 100

For example, if a price increases from $80 to $100:

Percentage increase = ((100 - 80) / 80) × 100 = (20/80) × 100 = 25%

Practical Applications of Percentages

Percentages are used in a wide array of fields. Here are some examples:

  • Finance: Calculating interest rates on loans, returns on investments, and percentage changes in stock prices.
  • Retail: Determining discounts, markups, and sales tax.
  • Statistics: Expressing data, such as the percentage of the population that supports a particular policy.
  • Healthcare: Calculating medication dosages, body fat percentage, and changes in patient vital signs.
  • Education: Grading student work, calculating attendance rates, and analyzing standardized test scores.
  • Science: Expressing concentrations of solutions, calculating error rates in experiments, and analyzing data.

Tips for Working with Percentages

  • Remember that 100% of a number is the number itself
  • To convert a percentage to a decimal, divide by 100
  • To convert a decimal to a percentage, multiply by 100
  • A percentage increase of 100% means the value has doubled
  • A percentage decrease of 100% means the value has become zero

Frequently Asked Questions (FAQs)

What is a percentage?

A percentage is a way of expressing a number as a fraction of 100. It's a ratio that shows how much of one quantity is contained within another.

How do I calculate a percentage of a number?

To find X% of Y, multiply Y by X/100. For example, to find 20% of 50, calculate (20/100) * 50 = 10.

How do I calculate percentage increase?

To calculate the percentage increase from an old value (OV) to a new value (NV), use the formula: ((NV - OV) / OV) * 100.

How do I calculate percentage decrease?

To calculate the percentage decrease from an old value (OV) to a new value (NV), use the formula: ((OV - NV) / OV) * 100.

How do I convert a percentage to a decimal?

To convert a percentage to a decimal, divide the percentage by 100. For example, 75% as a decimal is 75/100 = 0.75.

How do I convert a decimal to a percentage?

To convert a decimal to a percentage, multiply the decimal by 100. For example, 0.45 as a percentage is 0.45 * 100 = 45%.

What does "percent" mean?

"Percent" comes from the Latin "per centum," meaning "by the hundred." It indicates a ratio or fraction out of 100.

Can a percentage be greater than 100%?

Yes, a percentage can be greater than 100%. This indicates that the value is more than the original reference value. For example, a 200% increase means the new value is three times the original value.

Can a percentage be negative?

Yes, a percentage can be negative. This typically indicates a decrease or loss. For example, a -20% change means a 20% decrease.

How do I calculate the percentage difference between two numbers?

To calculate the percentage difference between two numbers, use the formula: |(A - B) / ((A + B) / 2)| * 100, where A and B are the two numbers. This gives the relative difference as a percentage.

What is the difference between percentage and percentile?

A percentage expresses a value as a fraction of 100, while a percentile indicates the value below which a given percentage of observations in a group of observations falls. For example, scoring in the 80th percentile means you scored higher than 80% of the other test-takers.

How are percentages used in everyday life?

Percentages are used extensively in everyday life, including calculating discounts while shopping, understanding interest rates on loans and savings accounts, determining tips at restaurants, and interpreting statistical data in news reports.