Percentage Calculator

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What is a Percentage Calculator?

A percentage calculator solves the three most common percentage problems: finding a percentage of a number, finding what percentage one number is of another, and calculating the change between two values. Pick the mode that matches your question and plug in two numbers.

How It Works

One formula for each mode:

X% of Y       = (X / 100) x Y
X is what % of Y = (X / Y) x 100
% change      = ((New - Old) / |Old|) x 100

Example

You scored 43 out of 50 on a test and want your percentage grade.

  • 43 / 50 x 100 = 86%

Your electricity bill went from $120 to $154. What is the increase?

  • (154 - 120) / 120 x 100 = 28.3% increase

Tips

  • To find 10% of any number, move the decimal one place to the left. 20% is double that.
  • Percentage change is directional: positive means an increase, negative means a decrease.
  • Percentages above 100% are valid. If something doubled, that is a 100% increase.

Frequently Asked Questions

What is a percentage?

A percentage is a number expressed as a fraction of 100. "50 percent" means 50 out of every 100, or one half. The word comes from the Latin "per centum," meaning by the hundred.

How do I calculate a percentage without a calculator?

10% is the number divided by 10. 5% is half of 10%. 25% is the number divided by 4. 50% is the number divided by 2. Combine these: 15% = 10% + 5%.

What is the difference between percentage and percentage points?

If interest rates rise from 2% to 3%, that is 1 percentage point higher but a 50% relative increase. Percentage points measure absolute difference; percentage change measures relative difference.

How do I reverse a percentage to find the original value?

Divide the final value by (1 + the percentage as a decimal). If a price is $132 after a 10% increase, the original was $132 / 1.10 = $120.