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Percentage Decrease Calculator

Calculate the percentage decrease between an original value and a new value.
Learn the percentage decrease formula with clear, step-by-step calculations.

01

Calculate Percentage Decrease

Enter the original value and the reduced value.

Try: 100 to 90 200 to 150 500 to 400
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YOUR RESULT

Percentage Decrease Result

From 100 to 80

20%

The value decreased by 20%. 20 units were reduced.

Absolute change: -20

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Calculation Breakdown

First, subtract the new value from the original value to find how much the value decreased.

Decrease = Original value − New value

= 100 − 80 = 20

Percentage decrease = (20 ÷ 100) × 100 = 20%

Formula Used

Percentage decrease compares the difference with the original value.

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

(100 − 80) ÷ 100 × 100 = 20%

The original value must be greater than zero because it is the denominator.

Step-by-Step Solution

Follow these steps to understand how the final percentage is obtained.

1
Find the change100 − 80 = 20
2
Divide the change by the original value20 ÷ 100 = 0.2
3
Multiply by 100 to convert to a percentage0.2 × 100 = 20%
LEARN THE CONCEPT

What Is Percentage Decrease?

Percentage decrease tells you how much a value has fallen compared with its original amount. For example, if a price drops from 100 to 80, the decrease is 20 units. Since 20 is one-fifth of the original 100, the percentage decrease is 20%.

This calculation is useful for discounts, price drops, reduced expenses, lower scores, and changes in sales or measurements. The new value is normally lower than the original value for a percentage decrease.

FORMULA EXPLAINED

How to Calculate Percentage Decrease

Subtract the new value from the original value to find the decrease. Divide the decrease by the original value, then multiply by 100.

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

From 100 to 80

Step 1: 100 − 80 = 20

Step 2: 20 ÷ 100 = 0.2

Step 3: 0.2 × 100

= 20% decrease

Percentage Decrease Examples

100 to 90= 10% decrease→ 200 to 150= 25% decrease→ 80 to 60= 25% decrease→ 500 to 400= 20% decrease→

Related Percentage Decrease Formulas

Percentage decrease(Original − New) ÷ Original × 100
Absolute changeNew value − Original value
New value after a decreaseOriginal × (1 − rate ÷ 100)
Original value before a decreaseNew ÷ (1 − rate ÷ 100)

For a decrease, subtract the new value from the original value before dividing by the original value. If the new value is higher, the values show an increase instead.

Percentage Decrease Calculator FAQs

What is the formula for percentage decrease?

Subtract the new value from the original value, divide that decrease by the original value, and multiply by 100: ((Original − New) ÷ Original) × 100.

What if the new value is higher than the original value?

If the new value is higher than the original value, the values show an increase instead. The signed percentage-decrease result will be negative, and the calculator explains that it is an increase.

Why can't the original value be zero?

The formula divides by the original value. Division by zero is undefined, so percentage decrease cannot be calculated from an original value of zero.

What is the difference between absolute change and percentage decrease?

Absolute change is the numerical difference between two values. Percentage decrease shows that difference relative to the original value.