Percentage Calculator

Calculate percentages, percentage difference and change, increases, decreases, discounts, percentage error, and missing values.

Enter the known values, leave the answer field blank, and select Calculate.

Percentage Calculator

Provide any two values below. The calculator solves the blank field.

Percentage Calculator in Common Phrases

What is%of

is what % of

is%of what?

Percentage Difference Calculator

Percentage Change Calculator

Enter any two values and leave the value you want to calculate blank.

Percentage Change Between Two Values

Compare a new value with its original value to find the percentage increase or decrease.

Discount Calculator

Find the amount saved and final price after a percentage discount.

Percentage Error Calculator

Compare an observed or measured value with the accepted actual value.

What does the Percentage Calculator calculate?

The Percentage Calculator converts the values you enter into a structured estimate using the formulas and assumptions documented on this page. Use the result to compare scenarios, review the calculation details, and identify sensitive inputs. Check the guide and formula sections before using the estimate for an important decision.

Percentage Calculator

Use this free percentage calculator to find a percentage of a number, determine what percentage one number is of another, work backward to find the original number, compare percentage difference, or calculate an increase or decrease. Each tool includes example values that you can select and replace.

How to Calculate a Percentage

A percentage describes a number as a portion of 100. To convert a percentage to a decimal, divide it by 100. For example, 18% becomes 0.18. To convert a decimal to a percentage, multiply it by 100. Review the Percentage Calculator assumptions before relying on this result for decisions.

18% =18100= 0.18

In the first calculator, enter any two of the percentage, base value, and result. Leave the unknown field blank and select Calculate. The completed equation is shown below the form.

Percentage Formulas

What is X percent of Y?

Convert the percentage to a decimal and multiply it by the base number. For a useful Percentage Calculator result, enter realistic values, compare relevant scenarios, check the calculation details, and review the definitions, assumptions, and limitations before using the estimate for an important decision.

Result =Percentage100× Base

EX:15100× 200 = 0.15 × 200 = 30

X is what percent of Y?

Divide the part by the whole, then multiply by 100. For a useful Percentage Calculator result, enter realistic values, compare relevant scenarios, check the calculation details, and review the definitions, assumptions, and limitations before using the estimate for an important decision.

Percentage =PartWhole× 100

EX:50200× 100 = 25%

X is Y percent of what number?

Convert the percentage to a decimal and divide the known part by that decimal. For a useful Percentage Calculator result, enter realistic values, compare relevant scenarios, check the calculation details, and review the definitions, assumptions, and limitations before using the estimate for an important decision.

Base =PartPercentage ÷ 100

EX:3015 ÷ 100= 30 ÷ 0.15 = 200

Percentage Difference Formula

Percentage difference compares two values without treating either one as the original. It divides their absolute difference by the average magnitude of the two values.

Percentage Difference =|V₁ − V₂|(V₁ + V₂)/2× 100

EX:|10 − 6|(10 + 6)/2=48= 0.5 = 50%

For 120 and 100, the difference is 20 and the average is 110. The percentage difference is approximately 18.18%.

Percentage Increase and Decrease

Percentage change compares a new value with an original value. Unlike percentage difference, the original value is the denominator, so reversing the two values can produce a different answer.

Percentage Change =New Value − Original ValueOriginal Value× 100

EX:50 − 4040× 100 = 25%

Increase a number by a percentage

New Value =Original Value ×(1 + Percentage100)

EX:500 ×(1 + 10100)= 500 × 1.10 = 550

Decrease a number by a percentage

New Value =Original Value ×(1 − Percentage100)

EX:500 ×(1 − 10100)= 500 × 0.90 = 450

For example, increasing 500 by 10% gives 550, while decreasing 500 by 10% gives 450. The percentage change calculator can also solve backward for the original value or percentage.

Discount Percentage Formula

A discount reduces an original price by a stated percentage. First calculate the amount saved, then subtract that amount from the original price.

Savings =Original Price ×Discount Percentage100

Final Price =Original Price − Savings

EX:120 ×25100= 30 saved; 120 − 30 = 90

Percentage Error Formula

Percentage error compares an observed or measured value with an accepted actual value. The absolute value keeps the reported error positive.

Percentage Error =|Observed − Actual||Actual|× 100

EX:|98 − 100|100× 100 = 2%

Common Percentage Examples

Question	Calculation	Answer
What is 20% of $80?	0.20 × 80	$16
45 is what percent of 60?	45 ÷ 60 × 100	75%
A $75 price increased by 8%	75 × 1.08	$81
A $120 price discounted by 25%	120 × 0.75	$90
Change from 40 to 50	(50 − 40) ÷ 40 × 100	25% increase

For more advanced expressions, parentheses, powers, or scientific functions, use the Scientific Calculator. For ordinary arithmetic, use the Basic Calculator.

Frequently asked questions

How do I find a percentage of a number?

Divide the percentage by 100 and multiply the decimal by the number. For example, 30% of 90 is 0.30 × 90 = 27. For a useful Percentage Calculator result, use realistic inputs, compare relevant scenarios, and review the stated assumptions before making a decision.

How do I find what percentage one number is of another?

Divide the first number by the second number and multiply by 100. The second number must not be zero. For a useful Percentage Calculator result, use realistic inputs, compare relevant scenarios, and review the stated assumptions before making a decision.

What is the difference between percentage change and percentage difference?

Percentage change compares a new value with a specific original value. Percentage difference compares two values using their average and does not assign either value as the original. Review the Percentage Calculator assumptions before relying on this result for decisions.

How do I calculate a percentage increase?

Multiply the original number by 1 plus the percentage written as a decimal. A 12% increase uses a multiplier of 1.12. For a useful Percentage Calculator result, use realistic inputs, compare relevant scenarios, and review the stated assumptions before making a decision.

How do I calculate a percentage decrease?

Multiply the original number by 1 minus the percentage written as a decimal. A 20% decrease uses a multiplier of 0.80. For a useful Percentage Calculator result, use realistic inputs, compare relevant scenarios, and review the stated assumptions before making a decision.

Can a percentage be greater than 100?

Yes. A result greater than 100% means the part is larger than the reference whole or the increase is larger than the original amount. Use realistic inputs and review the Percentage Calculator assumptions before relying on this result for decisions.

How do I calculate a sale discount?

Multiply the original price by the discount percentage divided by 100 to find the savings, then subtract the savings from the original price. For a useful Percentage Calculator result, use realistic inputs, compare relevant scenarios, and review the stated assumptions before making a decision.

What is percentage error?

Percentage error measures the absolute difference between an observed and actual value as a percentage of the actual value. For a useful Percentage Calculator result, use realistic inputs, compare relevant scenarios, and review the stated assumptions before making a decision.