Calculators

Algebra

Percent Calculators

Enter starting value and final value to find percentage decrease.

Input whole numbers or decimal numbers in the calculator. You can also use time values to find percentage decrease in amount of time. Enter time values in these formats where hh = hours, mm = minutes and ss = seconds:

• hh:mm
• mm:ss
• hh:mm:ss

How to Calculate Percentage Decrease

• Subtract starting value minus final value
• Divide that amount by the absolute value of the starting value
• Multiply by 100 to get percent decrease
• If the percentage is negative, it means there was an increase and not an decrease.

Percentage Decrease Formula

You can use the percentage decrease formula for any percent decrease calculation:

Watch the CalculatorSoup® YouTube video How to Calculate Percentage Decrease for some example calculations. We'll show you how to find percent decrease between two numbers, and also demonstrate how to use the CalculatorSoup Percentage Decrease Calculator above.

Example Problem: Percentage Decrease

You have a lamp with a 60-watt traditional light bulb. Your lamp uses 60 watts of electricity per hour. You're considering replacing the bulb with an LED light bulb that uses 8 watts of electricity per hour. What is the percentage decrease in the lamp's hourly energy use if you switch to an LED light bulb?

First, recall the formuula percentage decrease = [ (Starting Value - Final Value) / |Starting Value| ] × 100

Plug your numbers into the formula. V₁ is 60 and V₂ is 8.

60 - 8 = 52
52 / 60 = 0.8667
0.8667 × 100 = 86.67%

So if you switch to an LED light bulb your lamp will use 86.67% less energy per hour.

Related Calculators

Use the Percentage Increase Calculator to find the percent increase from one value to another.

Use the Percent Difference Calculator when you are comparing two values and want to find the percentage difference between them.

The Percent Change Calculator finds the change between two numbers as a percentage. It is similar to finding percentage increase or percentage decrease but it doesn't label the change as an increase or a decrease.