Percentage Calculator

Calculate percentages, percentage change, increase, and decrease with multiple modes.

How to Calculate Percentages

Percentages are used everywhere in daily life: discounts, taxes, tips, grades, statistics, and finance. This calculator supports five different percentage calculations, covering every common scenario you might encounter.

Percentage Formulas

  • What is X% of Y? Result = Y x (X / 100)
  • X is what % of Y? Percentage = (X / Y) x 100
  • Percentage Change: ((New - Old) / |Old|) x 100
  • Percentage Increase: Value x (1 + Percentage / 100)
  • Percentage Decrease: Value x (1 - Percentage / 100)

How to Use This Calculator

  1. Select the calculation mode: Choose which type of percentage calculation you need.
  2. Enter Value X: The first number (percentage or value, depending on mode).
  3. Enter Value Y: The second number.
  4. Click Calculate: Get the result with decimal and fraction equivalents.

Common Percentage Calculations

  • Sales tax: Price x Tax Rate% = Tax Amount
  • Discounts: Original Price x (1 - Discount%) = Sale Price
  • Tips: Bill x Tip% = Tip Amount
  • Grade percentages: Points Earned / Points Possible x 100
  • Investment returns: (Final - Initial) / Initial x 100

Percentage Tricks and Shortcuts

  • 10% of anything: Move the decimal point one place left. 10% of 85 = 8.5.
  • 5% of anything: Find 10% and divide by 2. 5% of 85 = 4.25.
  • 15% (for tips): Find 10% and add half of it. 15% of 85 = 8.5 + 4.25 = 12.75.
  • 25%: Divide by 4. 25% of 80 = 20.
  • X% of Y = Y% of X: 8% of 25 = 25% of 8 = 2 (pick whichever is easier!).

Percentage Calculator FAQ

How do I calculate a percentage?

To find X% of Y, multiply Y by X and divide by 100. For example, 25% of 200 = 200 x 25 / 100 = 50. To find what percentage X is of Y, divide X by Y and multiply by 100. For example, 50 is 25% of 200.

How do I calculate percentage change?

Percentage change = ((New Value - Old Value) / |Old Value|) x 100. For example, if a price goes from $80 to $100, the percentage change is ((100-80)/80) x 100 = 25% increase. If it drops to $60, it is ((60-80)/80) x 100 = -25% decrease.

How do I calculate a percentage increase?

To increase a number by a percentage: New Value = Original x (1 + Percentage/100). For example, $80 increased by 25% = $80 x 1.25 = $100. To find just the increase amount: $80 x 0.25 = $20.

How do I calculate a percentage decrease?

To decrease a number by a percentage: New Value = Original x (1 - Percentage/100). For example, $100 decreased by 20% = $100 x 0.80 = $80. The discount amount is $100 x 0.20 = $20.

How do I convert between fractions, decimals, and percentages?

Fraction to percentage: divide the numerator by denominator and multiply by 100 (3/4 = 0.75 = 75%). Decimal to percentage: multiply by 100 (0.75 = 75%). Percentage to decimal: divide by 100 (75% = 0.75).