How to Calculate Percentage Increase and Decrease

Introduction

Percentage increases and decreases are commonly used to compare how a value changes over time. They can help you understand changes in prices, salaries, sales, grades, populations, and many other real-world situations. This guide explains how to calculate both percentage increase and percentage decrease using simple formulas and examples.

What Is Percentage Increase?

A percentage increase shows how much a value has increased compared with its original value. It expresses the increase as a percentage of the original amount.

For example, if a price increases from $100 to $120, the increase is $20. Since $20 is 20% of the original $100, the percentage increase is 20%.

How to Calculate Percentage Increase

Use this formula:

Percentage Increase = ((New Value − Original Value) ÷ Original Value) × 100

Example

Suppose a product’s price increases from $100 to $125.

First, find the increase:

$125 − $100 = $25

Then divide the increase by the original value:

$25 ÷ $100 = 0.25

Multiply by 100:

0.25 × 100 = 25%

So, the price increased by 25%.

For a quick calculation, use our Percentage Increase Calculator.

What Is Percentage Decrease?

A percentage decrease shows how much a value has decreased compared with its original value.

For example, if a price falls from $100 to $80, the decrease is $20. That $20 represents 20% of the original $100, so the percentage decrease is 20%.

How to Calculate Percentage Decrease

Use this formula:

Percentage Decrease = ((Original Value − New Value) ÷ Original Value) × 100

Example

Suppose a product’s price decreases from $200 to $150.

First, find the decrease:

$200 − $150 = $50

Then divide by the original value:

$50 ÷ $200 = 0.25

Multiply by 100:

0.25 × 100 = 25%

So, the price decreased by 25%.

You can use our Percentage Decrease Calculator to calculate percentage decreases quickly.

Percentage Increase vs. Percentage Decrease

Although both calculations measure a change between two values, the direction of the change determines which formula you use.

Calculation	Formula
Percentage Increase	((New − Original) ÷ Original) × 100
Percentage Decrease	((Original − New) ÷ Original) × 100

The original value is important because it is the reference point used to calculate the percentage change.

Percentage Increase and Decrease Examples

Example 1: Price Increase

A product costs $50 and its price increases to $60.

Increase:

$60 − $50 = $10

Percentage increase:

($10 ÷ $50) × 100 = 20%

Answer: 20% increase

Example 2: Price Decrease

A jacket costs $120 and its price drops to $90.

Decrease:

$120 − $90 = $30

Percentage decrease:

($30 ÷ $120) × 100 = 25%

Answer: 25% decrease

Example 3: Salary Increase

A salary increases from $40,000 to $44,000.

Increase:

$44,000 − $40,000 = $4,000

Percentage increase:

($4,000 ÷ $40,000) × 100 = 10%

Answer: 10% increase

Where Are Percentage Increases and Decreases Used?

Percentage changes are useful in many everyday and professional situations.

Shopping

Compare price changes, discounts, and changes in product costs.

Business

Businesses can measure changes in revenue, sales, expenses, and profits.

Personal Finance

Percentage changes can help compare changes in savings, expenses, or income.

Education

Students can compare changes in scores or grades between tests.

Statistics

Percentage changes can help describe how values change between two periods.

How to Calculate Percentage Change Quickly

When you need to compare two values, first identify the original value and the new value.

If the new value is higher, you have an increase.

If the new value is lower, you have a decrease.

Then use the appropriate formula to calculate the percentage change.

For a faster calculation, you can use our Percentage Change Calculator.

Can a Percentage Increase Be Greater Than 100%?

Yes. A percentage increase can be greater than 100%.

For example, if a value increases from $50 to $150:

($150 − $50) ÷ $50 × 100 = 200%

The value increased by 200%.

Can a Percentage Decrease Be More Than 100%?

A standard percentage decrease from a positive starting value cannot be greater than 100% if the final value remains non-negative.

A decrease of 100% means the value has fallen to zero.

For example, a value decreasing from $100 to $0 represents a 100% decrease.