Percentage Calculator

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What is X% of Y?

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X is what percent of Y?

is what % of ?

Percentage Change

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Increase/Decrease by Percent

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How to Calculate Percentages

A percentage is a way of expressing a number as a fraction of 100. The word comes from the Latin "per centum," meaning "by the hundred."

Common Percentage Formulas

X% of Y = (X / 100) × Y
X is what % of Y = (X / Y) × 100
% Change = ((New − Old) / |Old|) × 100

Common Uses

How to Use This Percentage Calculator

Calculate percentages instantly with four different calculation modes. Find what percentage one number is of another, calculate percentage increases and decreases, or determine the result of applying a percentage to any number. Perfect for shopping discounts, tax calculations, grade percentages, and financial analysis.

  1. Choose a calculation mode: What is X% of Y, X is what % of Y, Percentage Change, or Increase/Decrease by %.
  2. Enter your numbers in the appropriate fields.
  3. Click Calculate to see instant results.
  4. Results appear immediately with no page reload needed.
  5. Switch between modes to perform different percentage calculations.

Understanding Percentages

A percentage represents a fraction of 100. The word comes from the Latin per centum, meaning by the hundred. Percentages are used everywhere in daily life, from sales tax and discounts to interest rates and exam scores. Understanding how to calculate percentages is a fundamental math skill.

Common Percentage Calculations

The most common percentage calculations include: finding a discount price (original price times (1 minus discount%)), calculating sales tax (price times tax rate), determining a tip (bill times tip%), computing interest (principal times rate times time), and figuring out grade percentages (points earned divided by total points times 100).

Percentage Change Formula

Percentage change measures how much a value has increased or decreased relative to its original value. The formula is: ((New Value minus Old Value) divided by Old Value) times 100. A positive result indicates an increase, while a negative result indicates a decrease. This is commonly used in finance, science, and business analytics.

Tips for Mental Math with Percentages

To quickly calculate 10% of any number, simply move the decimal point one place to the left. For 5%, halve the 10% result. For 15%, add 10% and 5% together. For 20%, double the 10% figure. For 25%, divide by 4. These shortcuts are especially useful when calculating tips at restaurants or estimating discounts while shopping.

Frequently Asked Questions

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

Divide the first number by the second number, then multiply by 100. For example, 25 is what percent of 200? (25 divided by 200) times 100 = 12.5%. This formula works for any two numbers.

How do I find the original price before a discount?

If you know the discounted price and the discount percentage, divide the discounted price by (1 minus discount/100). For example, if an item costs $80 after a 20% discount: $80 divided by 0.80 = $100 original price.

What is the difference between percentage and percentile?

A percentage is a fraction of 100 (e.g., 85% on a test means 85 out of 100). A percentile indicates ranking — the 85th percentile means you scored higher than 85% of all test-takers. They measure different things.

How do I calculate percentage increase between two numbers?

Use the formula: ((New minus Old) divided by Old) times 100. For example, if a stock goes from $50 to $75: ((75 minus 50) divided by 50) times 100 = 50% increase.

Can percentages be greater than 100?

Yes. A percentage over 100% means the value has more than doubled. For example, if a stock goes from $10 to $25, the increase is 150%. Percentages can also be negative, indicating a decrease.