Percentage Calculator

Solve any percentage problem instantly. Choose a calculation mode below: find a percentage of a number, determine what percent one number is of another, or calculate the percentage change between two values.

By Jordan Rivera|Updated Feb 15, 2026

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How to Calculate Percentages

A percentage is a way of expressing a number as a fraction of 100. The word "percent" literally means "per hundred." Understanding percentages is essential for everyday tasks including shopping discounts, tax calculations, tips, grades, and financial planning.

1. Finding a Percentage of a Number

To find X% of Y, use the formula:

Result = (X / 100) x Y

For example, 15% of 80 = (15 / 100) x 80 = 12. This is useful for calculating sales tax, discounts, and tips.

2. Finding What Percentage One Number Is of Another

To find what percent X is of Y, use the formula:

Percentage = (X / Y) x 100

For example, 45 out of 180 = (45 / 180) x 100 = 25%. This is useful for calculating grades, success rates, and proportions.

3. Calculating Percentage Change

To find the percentage change from an old value to a new value:

Percentage Change = ((New - Old) / |Old|) x 100

A positive result indicates an increase, while a negative result indicates a decrease. For example, going from 50 to 75 is a ((75-50)/50) x 100 = 50% increase.

Common Percentage Conversions

Fraction to percentage: Divide the numerator by the denominator, then multiply by 100. Example: 3/8 = 0.375 x 100 = 37.5%
Decimal to percentage: Multiply by 100. Example: 0.65 = 65%
Percentage to decimal: Divide by 100. Example: 42% = 0.42
Percentage to fraction: Put the percentage over 100 and simplify. Example: 75% = 75/100 = 3/4

Real-World Percentage Examples

Shopping discount: A $120 jacket is 30% off. Discount = (30/100) x 120 = $36. Sale price = $120 - $36 = $84.
Restaurant tip: A $65 meal with a 20% tip. Tip = (20/100) x 65 = $13. Total = $65 + $13 = $78.
Sales tax: A $50 item with 8.5% tax. Tax = (8.5/100) x 50 = $4.25. Total = $54.25.
Grade calculation: You scored 42 out of 50. Percentage = (42/50) x 100 = 84%.
Price increase: Gas went from $3.20 to $3.84. Change = ((3.84 - 3.20) / 3.20) x 100 = 20% increase.

Frequently Asked Questions

How do I calculate a percentage of a number?

To calculate a percentage of a number, multiply the number by the percentage and divide by 100. For example, to find 25% of 200, calculate (25 x 200) / 100 = 50. Alternatively, convert the percentage to a decimal first (25% = 0.25) and multiply: 0.25 x 200 = 50.

How do I calculate percentage increase or decrease?

To calculate percentage change, subtract the old value from the new value, divide by the old value, and multiply by 100. The formula is: ((New Value - Old Value) / Old Value) x 100. If the result is positive, it is an increase. If negative, it is a decrease. For example, going from 80 to 100 is a ((100-80)/80) x 100 = 25% increase.

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

To find what percentage one number is of another, divide the first number by the second number and multiply by 100. The formula is: (Part / Whole) x 100 = Percentage. For example, to find what percent 30 is of 150, calculate (30 / 150) x 100 = 20%. So 30 is 20% of 150.

What is the formula for percentage?

The basic percentage formula is: Percentage = (Part / Whole) x 100. This can be rearranged to solve different types of problems: Part = (Percentage x Whole) / 100, or Whole = (Part / Percentage) x 100. For percentage change: ((New - Old) / Old) x 100.

How do I convert a fraction to a percentage?

To convert a fraction to a percentage, divide the numerator by the denominator and multiply by 100. For example, 3/4 = 0.75, and 0.75 x 100 = 75%. Common conversions: 1/2 = 50%, 1/3 = 33.33%, 1/4 = 25%, 1/5 = 20%, 3/4 = 75%, 2/3 = 66.67%.