Enter the total decay and the original starting amount into the Calculator. The calculator will evaluate the Decay Percentage. 

Decay Percentage Formula

DP = TD / OA *100


  • DP is the Decay Percentage (%)
  • TD is the total decay
  • OA is the original starting amount

To calculate the Decay Percentage, divide the total decay amount by the original starting amount, then multiply by 100.

How to Calculate Decay Percentage?

The following steps outline how to calculate the Decay Percentage.

  1. First, determine the total decay. 
  2. Next, determine the original starting amount. 
  3. Next, gather the formula from above = DP = TD / OA *100.
  4. Finally, calculate the Decay Percentage.
  5. After inserting the variables and calculating the result, check your answer with the calculator above.

Example Problem : 

Use the following variables as an example problem to test your knowledge.

total decay = 16

original starting amount = 80

Frequently Asked Questions (FAQ)

What is decay percentage and why is it important?
Decay percentage measures the proportion of a substance or quantity that has decreased over a period of time. It is important in fields such as chemistry, physics, and finance to understand how quickly substances degrade or investments decrease in value.

Can the decay percentage formula be used for any type of decay?
Yes, the decay percentage formula (DP = TD / OA * 100) can be applied to various types of decay as long as you can quantify the total decay and the original amount. This includes radioactive decay, biological decay, and financial depreciation.

How can I check if my decay percentage calculation is accurate?
After calculating the decay percentage using the formula, you can verify your result by using one of the calculators provided in the links above. These calculators are designed to help ensure the accuracy of your calculations.

What is the difference between decay constant and decay factor?
The decay constant is a parameter that describes the rate at which a quantity decays over time, typically expressed in units of time-1. The decay factor, on the other hand, is a multiplier that describes how much of the original quantity remains after a certain period. Both are related to the decay process but from different perspectives.