Enter the number of colonies, dilution factor, and volume of the culture plate into the calculator to determine the bacterial concentration.

## Bacterial Concentration Formula

The following formula is used to calculate a bacterial concentration.

BC = C * DF / VC
• Where BC is the bacterial concentration (cfu/ml)
• #C is the number of colonies
• DF is the dilution factor
• VC is the volume of the culture plate (ml)

To calculate a bacterial concentration, multiply the number of colonies by the dilution factor, then divide by the volume of the culture plate.

## What is a bacterial concentration?

A bacterial concentration is a measure of the total number of bacteria per unit of weight or volume. This is typically measured in colony-forming units per milliliter of culture.

## How to claculate bacterial concentration?

The following example problem outlines the steps needed to calculate a bacterial concentration.

First, determine the number of colonies. In this example, the number of colonies is 50.

Next, determine the dilution factor. This solution is diluted by a factor of 1:2 = .5.

Next, determine the total volume of the culture plate. In this case, the total volume is 20ml.

Finally, calculate the bacterial concentration using the formula above:

BC = #C * DF / VC

BC = 50 * .5 / 20

BC = 1.25 CFU/ml