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Explanations that go deeper than a calculator result: the formulas, the steps, the worked examples and the mistakes to avoid — each article links to the calculator that does the math for you.

Diagram showing an increase from 80 dollars to 100 dollars, a change of 20 dollars equal to a 25 percent increase

How to Calculate Percentage Increase and Decrease (Step by Step)

Learn how to calculate percentage increase and decrease step by step, with clear formulas, worked examples, common mistakes to avoid, and a free calculator.

Math · October 21, 2026 →

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Our longer reference guides live alongside the blog: