There are various advantages of using serial dilution in microbiology. 

• Serial dilution helps to gradually decrease a high concentrate cell culture to a more manageable and practical level. 
• Counting the colonies obtained from these samples helps estimate the concentration of an unknown substance. 
• The known concentration solution is measured just once. As the concentration decreases with each step, the error margin in each subsequent standard decreases significantly. 
• Having evenly spaced standards enhances the reliability of the analysis results. 
• This method is also advantageous when the calibration standards need to cover a wide range of concentrations.