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Percentage Calculator

Calculate percentages, percentage increase/decrease, percentage change, and solve various percentage problems.

What is X% of Y?

Calculate what value represents a certain percentage of another number.

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Common Examples:

X is what % of Y?

Find what percentage one number is of another.

Common Examples:

X is Y% of what?

Find the original value when you know the percentage and result.

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Common Examples:

Percentage Change

Calculate the percentage change from one value to another.

Common Examples:

Increase or Decrease by Percentage

Calculate the result after increasing or decreasing a value by a percentage.

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Common Examples:

Percentage Formulas

Basic Calculations

  • X% of Y: (X / 100) x Y
  • X is what % of Y: (X / Y) x 100
  • X is Y% of what: X / (Y / 100)

Change Calculations

  • Percentage Change: ((New - Old) / Old) x 100
  • Add X%: Number x (1 + X/100)
  • Subtract X%: Number x (1 - X/100)

Percentage vs. Percentage Points

Important distinction:

  • Percentage change: From 40% to 50% is a 25% increase [(50-40)/40 x 100]
  • Percentage point change: From 40% to 50% is a 10 percentage point increase [50-40]

Common Percentages to Remember

Percentage Decimal Fraction Quick Tip
100%1.01/1The whole amount
75%0.753/4Three quarters
50%0.51/2Half
33.33%0.333...1/3One third
25%0.251/4Quarter
20%0.21/5Double 10%
10%0.11/10Move decimal left once

Mental Math Tricks

  • 10%: Move decimal point left one place (10% of 250 = 25)
  • 5%: Half of 10% (5% of 250 = 12.5)
  • 15%: 10% + 5% (useful for tips)
  • 20%: Double 10% (20% of 250 = 50)
  • 25%: Divide by 4 (25% of 80 = 20)
  • 50%: Divide by 2 (50% of 80 = 40)

Common Percentage Uses

Shopping & Sales

  • Calculate discounts
  • Find sale prices
  • Determine savings
  • Calculate tax amounts

Finance

  • Interest rates
  • Investment returns
  • Loan calculations
  • Budget allocations
  • Profit margins
  • Inflation rates

Statistics & Science

  • Grade calculations
  • Survey results
  • Growth rates
  • Data analysis
  • Margins of error
  • Confidence levels

Examples

  • Shopping: A $50 shirt is 20% off. Sale price: $50 - (20% of $50) = $50 - $10 = $40
  • Grade: You got 45 out of 60 questions correct. Your score: (45/60) x 100 = 75%
  • Raise: Your salary increased from $50,000 to $55,000. Increase: ((55,000-50,000)/50,000) x 100 = 10%
  • Tax: A $100 item with 8% tax. Total: $100 + (8% of $100) = $100 + $8 = $108
  • Tip: 15% tip on a $60 bill: (15/100) x 60 = $9 tip, total = $69
  • Reverse: You paid $15 tip which was 20% of the bill. Bill = $15 / 0.20 = $75

Related Utils

Average Calculator Complex Number Fractions Scientific Mean, Median, Mode Standard Deviation

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