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Percent Decrease Calculator

Free percent decrease calculator. Find the new value after a percentage decrease. Calculate discounts, depreciation, and reductions instantly.

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Understanding results

The calculator displays:

  • New Value: The final amount after the percentage decrease
  • Decrease Amount: How much was subtracted from the original
  • Original Value: Your starting number for reference

This breakdown helps you understand both the final value and how much was reduced.

Purpose

The percent decrease calculator helps you determine the new value after reducing an original number by a specific percentage. Whether you're calculating sale prices, depreciation, weight loss, or any reduction, this tool provides accurate results instantly.

Understanding percent decrease is essential for shopping (calculating discount prices), finance (asset depreciation), health (weight or calorie reduction), and business (cost cutting). This calculator does the math for you and shows the step-by-step breakdown.

How to use

Using the percent decrease calculator is straightforward:

  1. Enter the Original Value: Input the starting number (e.g., original price, starting weight, initial value).
  2. Enter the Percentage Decrease: Input the percentage you want to decrease by (e.g., 20 for a 20% decrease).
  3. View Results: The calculator shows the new value after the decrease and how much was reduced.

Examples

Example 1: Sale Price

A $150 jacket is 40% off.

  • Sale Price = $150 × 0.60 = $90
  • You save $60.

Example 2: Weight Loss

Starting weight is 200 lbs, goal is to lose 15%.

  • Target Weight = 200 × 0.85 = 170 lbs
  • Weight to lose: 30 lbs.

Example 3: Depreciation

A car worth $25,000 depreciates 20% in the first year.

  • Value After 1 Year = $25,000 × 0.80 = $20,000

How it works

Formula: New Value = Original Value × (1 - Percentage ÷ 100)

The formula converts the percentage to a decimal, subtracts from 1 to get the remaining portion, then multiplies by the original value.

Example: $100 decreased by 30%

  • Convert: 30% = 0.30
  • Subtract from 1: 1 - 0.30 = 0.70
  • Multiply: $100 × 0.70 = $70

FAQ

How do I calculate percent decrease?

To calculate percent decrease: multiply the original value by (1 - percentage/100). For example, $100 decreased by 20% = $100 × 0.80 = $80.

What is the formula for percentage decrease?

The formula is: New Value = Original Value × (1 - Percentage ÷ 100). Alternatively: New Value = Original Value - (Original Value × Percentage ÷ 100).

How do I calculate a 30% decrease?

Multiply your original value by 0.70 (which is 1 - 0.30). For example, $200 with a 30% decrease = $200 × 0.70 = $140.

What is the difference between percent decrease and percent off?

They are the same concept. 'Percent off' is commonly used in retail to describe discounts, while 'percent decrease' is the mathematical term. A 25% off sale means a 25% decrease in price.

Can a value decrease by more than 100%?

Mathematically, a 100% decrease means the value becomes zero. A decrease greater than 100% would result in a negative value, which may not be meaningful in most real-world contexts.

Methodology

The percent decrease formula is:

New Value = Original Value × (1 - Percentage/100)

Or equivalently:

Decrease Amount = Original Value × (Percentage/100)
New Value = Original Value - Decrease Amount

Example Calculation

A $80 item is on sale for 25% off:

  • Decrease Amount = $80 × (25/100) = $20
  • Sale Price = $80 - $20 = $60

Validation & Accuracy

Tested: Verified against Excel, Google Sheets, and scientific calculators.

Accuracy: Results are mathematically exact, rounded to 2 decimal places.

Sources

Based on standard mathematical principles for percentage calculations used in retail, finance, and business applications.