By using a known volume of the sample, you can extrapolate the number of CFUs per plate to CFU per ml of bacteria culture or grams of sample. The general formula to calculate CFU/ml is well known: The number of microbes/ml = number of colonies x dilution of the sample.
The colony counting problem can be easily solved by using the "CountThings By Camera" mobile app. You only need to take a photo, click to identify, and the whole process can be automatically completed, and the accuracy can also be adjusted.
You can download it at google play named "CountThings By Camera"
