Most bacterial cells range in size from 0.2 to 10 microns or micrometers (0.0000079 to 0.00039 inches). Common Escherichia coli, or E. coli, bacteria are rod-shaped bacteria, 1 micron by 2 microns long.
According to many microbiology books, the average size of most bacteria is between 0.2 and 2.0 micrometer (diameter). However, there are some that hold this to range between 1 and 10 micrometers.