Log Reduction Calculator

Use our online log reduction calculator tool that helps you to calculate the no.of microorganisms before and after treatment that can be expressed as logs and percentages easily in a fraction of seconds. To use this calculator, all you need to do is give the inputs in the input fields and then click on the calculate button. So that you will get answers instantly.

Initial CFU amount
CFU
Final CFU amount
CFU

Log reduction calculator provides a simple method to calculate the efficacy of disinfectants such as alcohol or bleach. This tool works by comparing the number of microorganisms in a sample before and after the treatment. The collected results are then expressed as a percentage and as on the logarithmic scale. Higher result mean that the given agent has a higher efficacy.

Log Reduction Calculator: Are you looking for a tool to calculate the log and percentage reduction? Then you are on the right page. We have provided you with the log reduction calculator to get easy outputs. And also we provided complete information about the log reduction like definitions, formulas, examples, and many more!!

What is Log Reduction?

It is a simple way of showing the reduction that is available in microorganisms before and after treatment called log reduction. And this log reduction is a mathematical term. Using logs is very useful as that reduces the large numbers into simple ones.

Log reduction Formula

Here we are going to look into the log reduction formulas.

Log Reduction = log10(initial CFU/final CFU)

For changing the log answer to the percentage value we use this formula

Percentage Reduction = 100 x (initial CFU - final CFU)/initial CFU

Log Reduction Chart

Look into the chart that was given below for log reduction.

Log Reduction Percent Reduced
1 90%
2 99%
3 99.9%
4 99.99%
5 99.999%
6 99.9999%

How do you Calculate Log Reduction?

Following are the simple steps that help you to calculate the log reduction easily.

  • Firstly, take the values that are given in the problem.
  • Determine the no.of organisms before treatment.
  • Then, determine the no.of organisms after treatment.
  • Apply the formula of log reduction.
  • Substitute the values and simplify them.
  • Finally, you will get the answers easily.

Example Problem for Log Reduction

Question: Find the log and percentage reduction if the initial CFU amount is 765 x 107, the final CFU amount is 876 x 105.

Solution:

Given,

initial CFU amount = 765 x 107

final CFU amount = 876 x 105

Apply the formula,

Log Reduction = log10(initial CFU/final CFU)

Log reduction = log10(765 x 107/876 x 105)

Log reduction = 1.941.

Now, calculate the percentage reduction by using the formula.

Percentage Reduction = 100 x (initial CFU - final CFU)/initial CFU

= 100 x (765 x 107-876 x 105)/765 x 107

Percentage reduction = 98.855%

Hence the values of log and percentage reduction are 1 and 98%.

For more biology calculators, you can click on our onlinecalculator.guide website.

FAQs on Log Reduction Calculator

1. How do you calculate log reduction?

To calculate the log reduction, we use the formula, Log Reduction = log10(initial CFU/final CFU)

2. How to use a log reduction calculator?

Simply, give the inputs in the input fields and then click on the calculate button that provides you the answers instantly.

3. What is 1 log reduction?

1 log reduction is equal to 90% of the percentage reduction.