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Percentage Calculator

Calculate percentages three ways: find a percentage of a number, find what percent one number is of another, or calculate percentage change.

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Three Ways to Calculate a Percentage

Percentage questions usually come in one of three shapes. X% of Y finds a portion of a number (e.g. "what is 20% of 150?"). X is what % of Y finds the relationship between two numbers (e.g. "30 is what percent of 150?"). Percentage change finds how much a value has grown or shrunk between two points (e.g. "from 80 to 100 is what % increase?").

Example Calculation

20% of 150 = 30.

30 is what % of 150? → 20%.

Going from 80 to 100 is a 25% increase.

Formula / Calculation Method

X% of Y = (X ÷ 100) × Y.
X is what % of Y = (X ÷ Y) × 100.
% Change = [(New − Old) ÷ |Old|] × 100.

How to Use This Tool

  1. Choose the tab that matches your question.
  2. Enter the two numbers involved.
  3. Click Calculate to see the result instantly.

Common Use Cases

Calculating tips, tax, or discounts
Working out grade or test percentages
Measuring growth or decline between two values
Everyday percentage math for school or work

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Frequently Asked Questions

How do I calculate a percentage increase?

Subtract the old value from the new value, divide by the old value, then multiply by 100. A positive result is an increase; a negative result is a decrease.

Can percentages be negative?

The percentage change result can be negative, which represents a decrease. The other two modes typically use positive numbers, but negative inputs are calculated the same way mathematically.